Actual source code: ts.c

  1: #include <petsc/private/tsimpl.h>
  2: #include <petscdmda.h>
  3: #include <petscdmshell.h>
  4: #include <petscdmplex.h>
  5: #include <petscdmswarm.h>
  6: #include <petscviewer.h>
  7: #include <petscdraw.h>
  8: #include <petscconvest.h>

 10: /* Logging support */
 11: PetscClassId  TS_CLASSID, DMTS_CLASSID;
 12: PetscLogEvent TS_Step, TS_PseudoComputeTimeStep, TS_FunctionEval, TS_JacobianEval;

 14: const char *const TSExactFinalTimeOptions[] = {"UNSPECIFIED", "STEPOVER", "INTERPOLATE", "MATCHSTEP", "TSExactFinalTimeOption", "TS_EXACTFINALTIME_", NULL};

 16: static PetscErrorCode TSAdaptSetDefaultType(TSAdapt adapt, TSAdaptType default_type)
 17: {
 18:   PetscFunctionBegin;
 20:   PetscAssertPointer(default_type, 2);
 21:   if (!((PetscObject)adapt)->type_name) PetscCall(TSAdaptSetType(adapt, default_type));
 22:   PetscFunctionReturn(PETSC_SUCCESS);
 23: }

 25: /*@
 26:   TSSetFromOptions - Sets various `TS` parameters from the options database

 28:   Collective

 30:   Input Parameter:
 31: . ts - the `TS` context obtained from `TSCreate()`

 33:   Options Database Keys:
 34: + -ts_type type                                                      - see `TSType`
 35: . -ts_save_trajectory                                                - checkpoint the solution at each time-step
 36: . -ts_max_time time                                                  - maximum time to compute to
 37: . -ts_time_span t0,...,tf                                            - sets the time span, solutions are computed and stored for each indicated time, init_time and max_time are set
 38: . -ts_eval_times t0,...,tn                                           - time points where solutions are computed and stored for each indicated time
 39: . -ts_max_steps steps                                                - maximum time-step number to execute until (possibly with nonzero starting value)
 40: . -ts_run_steps steps                                                - maximum number of time steps for `TSSolve()` to take on each call
 41: . -ts_init_time time                                                 - initial time to start computation
 42: . -ts_final_time time                                                - final time to compute to (deprecated: use `-ts_max_time`)
 43: . -ts_time_step dt                                                   - initial time step (only a suggestion, the actual initial time step used differ)
 44: . -ts_exact_final_time (stepover,interpolate,matchstep)              - whether to stop at the exact given final time and how to compute the solution at that time
 45: . -ts_max_snes_failures maxfailures                                  - Maximum number of nonlinear solve failures allowed
 46: . -ts_max_step_rejections maxrejects                                 - Maximum number of step rejections before step fails
 47: . -ts_error_if_step_fails (true|false)                               - Error if no step succeeds
 48: . -ts_rtol rtol                                                      - relative tolerance for local truncation error
 49: . -ts_atol atol                                                      - Absolute tolerance for local truncation error
 50: . -ts_rhs_jacobian_test_mult -mat_shell_test_mult_view               - test the Jacobian at each iteration against finite difference with RHS function
 51: . -ts_rhs_jacobian_test_mult_transpose                               - test the Jacobian at each iteration against finite difference with RHS function
 52: . -ts_adjoint_solve (true|false)                                     - After solving the ODE/DAE solve the adjoint problem (requires `-ts_save_trajectory`)
 53: . -ts_fd_color                                                       - Use finite differences with coloring to compute IJacobian
 54: . -ts_monitor                                                        - print information at each timestep
 55: . -ts_monitor_cancel                                                 - Cancel all monitors
 56: . -ts_monitor_wall_clock_time                                        - Monitor wall-clock time, `KSP` iterations, and `SNES` iterations per step
 57: . -ts_monitor_lg_solution                                            - Monitor solution graphically
 58: . -ts_monitor_lg_error                                               - Monitor error graphically
 59: . -ts_monitor_error                                                  - Monitors norm of error
 60: . -ts_monitor_lg_timestep                                            - Monitor timestep size graphically
 61: . -ts_monitor_lg_timestep_log                                        - Monitor log timestep size graphically
 62: . -ts_monitor_lg_snes_iterations                                     - Monitor number nonlinear iterations for each timestep graphically
 63: . -ts_monitor_lg_ksp_iterations                                      - Monitor number nonlinear iterations for each timestep graphically
 64: . -ts_monitor_sp_eig                                                 - Monitor eigenvalues of linearized operator graphically
 65: . -ts_monitor_draw_solution                                          - Monitor solution graphically
 66: . -ts_monitor_draw_solution_phase  xleft,yleft,xright,yright         - Monitor solution graphically with phase diagram, requires problem with exactly 2 degrees of freedom
 67: . -ts_monitor_draw_error                                             - Monitor error graphically, requires use to have provided TSSetSolutionFunction()
 68: . -ts_monitor_solution [ascii binary draw][:filename][:viewerformat] - monitors the solution at each timestep
 69: . -ts_monitor_solution_interval interval                             - output once every interval (default=1) time steps. Use -1 to only output at the end of the simulation
 70: . -ts_monitor_solution_skip_initial                                  - skip writing of initial condition
 71: . -ts_monitor_solution_vtk filename.vts,filename.vtu                 - Save each time step to a binary file, use filename-%%03" PetscInt_FMT ".vts (filename-%%03" PetscInt_FMT ".vtu)
 72: . -ts_monitor_solution_vtk_interval interval                         - output once every interval (default=1) time steps. Use -1 to only output at the end of the simulation
 73: - -ts_monitor_envelope                                               - determine maximum and minimum value of each component of the solution over the solution time

 75:   Level: beginner

 77:   Notes:
 78:   See `SNESSetFromOptions()` and `KSPSetFromOptions()` for how to control the nonlinear and linear solves used by the time-stepper.

 80:   Certain `SNES` options get reset for each new nonlinear solver, for example `-snes_lag_jacobian its` and `-snes_lag_preconditioner its`, in order
 81:   to retain them over the multiple nonlinear solves that `TS` uses you must also provide `-snes_lag_jacobian_persists true` and
 82:   `-snes_lag_preconditioner_persists true`

 84:   Developer Notes:
 85:   We should unify all the -ts_monitor options in the way that -xxx_view has been unified

 87: .seealso: [](ch_ts), `TS`, `TSGetType()`
 88: @*/
 89: PetscErrorCode TSSetFromOptions(TS ts)
 90: {
 91:   PetscBool              opt, flg, tflg;
 92:   char                   monfilename[PETSC_MAX_PATH_LEN];
 93:   PetscReal              time_step, eval_times[100] = {0};
 94:   PetscInt               num_eval_times = PETSC_STATIC_ARRAY_LENGTH(eval_times);
 95:   TSExactFinalTimeOption eftopt;
 96:   char                   dir[16];
 97:   TSIFunctionFn         *ifun;
 98:   const char            *defaultType;
 99:   char                   typeName[256];

101:   PetscFunctionBegin;

104:   PetscCall(TSRegisterAll());
105:   PetscCall(TSGetIFunction(ts, NULL, &ifun, NULL));

107:   PetscObjectOptionsBegin((PetscObject)ts);
108:   if (((PetscObject)ts)->type_name) defaultType = ((PetscObject)ts)->type_name;
109:   else defaultType = ifun ? TSBEULER : TSEULER;
110:   PetscCall(PetscOptionsFList("-ts_type", "TS method", "TSSetType", TSList, defaultType, typeName, sizeof(typeName), &opt));
111:   if (opt) PetscCall(TSSetType(ts, typeName));
112:   else PetscCall(TSSetType(ts, defaultType));

114:   /* Handle generic TS options */
115:   PetscCall(PetscOptionsDeprecated("-ts_final_time", "-ts_max_time", "3.10", NULL));
116:   PetscCall(PetscOptionsReal("-ts_max_time", "Maximum time to run to", "TSSetMaxTime", ts->max_time, &ts->max_time, NULL));
117:   PetscCall(PetscOptionsRealArray("-ts_time_span", "Time span", "TSSetTimeSpan", eval_times, &num_eval_times, &flg));
118:   if (flg) PetscCall(TSSetTimeSpan(ts, num_eval_times, eval_times));
119:   num_eval_times = PETSC_STATIC_ARRAY_LENGTH(eval_times);
120:   PetscCall(PetscOptionsRealArray("-ts_eval_times", "Evaluation time points", "TSSetEvaluationTimes", eval_times, &num_eval_times, &opt));
121:   PetscCheck(flg != opt || (!flg && !opt), PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "May not provide -ts_time_span and -ts_eval_times simultaneously");
122:   if (opt) PetscCall(TSSetEvaluationTimes(ts, num_eval_times, eval_times));
123:   PetscCall(PetscOptionsInt("-ts_max_steps", "Maximum time step number to execute to (possibly with non-zero starting value)", "TSSetMaxSteps", ts->max_steps, &ts->max_steps, NULL));
124:   PetscCall(PetscOptionsInt("-ts_run_steps", "Maximum number of time steps to take on each call to TSSolve()", "TSSetRunSteps", ts->run_steps, &ts->run_steps, NULL));
125:   PetscCall(PetscOptionsReal("-ts_init_time", "Initial time", "TSSetTime", ts->ptime, &ts->ptime, NULL));
126:   PetscCall(PetscOptionsDeprecated("-ts_dt", "-ts_time_step", "3.25", NULL));
127:   PetscCall(PetscOptionsReal("-ts_time_step", "Initial time step", "TSSetTimeStep", ts->time_step, &time_step, &flg));
128:   if (flg) PetscCall(TSSetTimeStep(ts, time_step));
129:   PetscCall(PetscOptionsEnum("-ts_exact_final_time", "Option for handling of final time step", "TSSetExactFinalTime", TSExactFinalTimeOptions, (PetscEnum)ts->exact_final_time, (PetscEnum *)&eftopt, &flg));
130:   if (flg) PetscCall(TSSetExactFinalTime(ts, eftopt));
131:   PetscCall(PetscOptionsInt("-ts_max_snes_failures", "Maximum number of nonlinear solve failures", "TSSetMaxSNESFailures", ts->max_snes_failures, &ts->max_snes_failures, &flg));
132:   if (flg) PetscCall(TSSetMaxSNESFailures(ts, ts->max_snes_failures));
133:   PetscCall(PetscOptionsDeprecated("-ts_max_reject", "-ts_max_step_rejections", "3.25", NULL));
134:   PetscCall(PetscOptionsInt("-ts_max_step_rejections", "Maximum number of step rejections before step fails", "TSSetMaxStepRejections", ts->max_reject, &ts->max_reject, &flg));
135:   if (flg) PetscCall(TSSetMaxStepRejections(ts, ts->max_reject));
136:   PetscCall(PetscOptionsBool("-ts_error_if_step_fails", "Error if no step succeeds", "TSSetErrorIfStepFails", ts->errorifstepfailed, &ts->errorifstepfailed, NULL));
137:   PetscCall(PetscOptionsBoundedReal("-ts_rtol", "Relative tolerance for local truncation error", "TSSetTolerances", ts->rtol, &ts->rtol, NULL, 0));
138:   PetscCall(PetscOptionsBoundedReal("-ts_atol", "Absolute tolerance for local truncation error", "TSSetTolerances", ts->atol, &ts->atol, NULL, 0));

140:   PetscCall(PetscOptionsBool("-ts_rhs_jacobian_test_mult", "Test the RHS Jacobian for consistency with RHS at each solve ", "None", ts->testjacobian, &ts->testjacobian, NULL));
141:   PetscCall(PetscOptionsBool("-ts_rhs_jacobian_test_mult_transpose", "Test the RHS Jacobian transpose for consistency with RHS at each solve ", "None", ts->testjacobiantranspose, &ts->testjacobiantranspose, NULL));
142:   PetscCall(PetscOptionsBool("-ts_use_splitrhsfunction", "Use the split RHS function for multirate solvers ", "TSSetUseSplitRHSFunction", ts->use_splitrhsfunction, &ts->use_splitrhsfunction, NULL));
143: #if PetscDefined(HAVE_SAWS)
144:   {
145:     PetscBool set;
146:     flg = PETSC_FALSE;
147:     PetscCall(PetscOptionsBool("-ts_saws_block", "Block for SAWs memory snooper at end of TSSolve", "PetscObjectSAWsBlock", ((PetscObject)ts)->amspublishblock, &flg, &set));
148:     if (set) PetscCall(PetscObjectSAWsSetBlock((PetscObject)ts, flg));
149:   }
150: #endif

152:   /* Monitor options */
153:   PetscCall(PetscOptionsDeprecated("-ts_monitor_frequency", "-ts_dmswarm_monitor_moments_interval", "3.24", "Retired in favor of monitor-specific intervals (ts_dmswarm_monitor_moments was the only monitor to use ts_monitor_frequency)"));
154:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor", "Monitor time and timestep size", "TSMonitorDefault", TSMonitorDefault, NULL));
155:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_wall_clock_time", "Monitor wall-clock time, KSP iterations, and SNES iterations per step", "TSMonitorWallClockTime", TSMonitorWallClockTime, TSMonitorWallClockTimeSetUp));
156:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_extreme", "Monitor extreme values of the solution", "TSMonitorExtreme", TSMonitorExtreme, NULL));
157:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_solution", "View the solution at each timestep", "TSMonitorSolution", TSMonitorSolution, TSMonitorSolutionSetup));
158:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_dmswarm_monitor_moments", "Monitor moments of particle distribution", "TSDMSwarmMonitorMoments", TSDMSwarmMonitorMoments, NULL));
159:   PetscCall(PetscOptionsString("-ts_monitor_python", "Use Python function", "TSMonitorSet", NULL, monfilename, sizeof(monfilename), &flg));
160:   if (flg) PetscCall(PetscPythonMonitorSet((PetscObject)ts, monfilename));

162:   PetscCall(PetscOptionsName("-ts_monitor_lg_solution", "Monitor solution graphically", "TSMonitorLGSolution", &opt));
163:   if (opt) {
164:     PetscInt  howoften = 1;
165:     DM        dm;
166:     PetscBool net;

168:     PetscCall(PetscOptionsInt("-ts_monitor_lg_solution", "Monitor solution graphically", "TSMonitorLGSolution", howoften, &howoften, NULL));
169:     PetscCall(TSGetDM(ts, &dm));
170:     PetscCall(PetscObjectTypeCompare((PetscObject)dm, DMNETWORK, &net));
171:     if (net) {
172:       TSMonitorLGCtxNetwork ctx;
173:       PetscCall(TSMonitorLGCtxNetworkCreate(ts, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 600, 400, howoften, &ctx));
174:       PetscCall(TSMonitorSet(ts, TSMonitorLGCtxNetworkSolution, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxNetworkDestroy));
175:       PetscCall(PetscOptionsBool("-ts_monitor_lg_solution_semilogy", "Plot the solution with a semi-log axis", "", ctx->semilogy, &ctx->semilogy, NULL));
176:     } else {
177:       TSMonitorLGCtx ctx;
178:       PetscCall(TSMonitorLGCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
179:       PetscCall(TSMonitorSet(ts, TSMonitorLGSolution, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
180:     }
181:   }

183:   PetscCall(PetscOptionsName("-ts_monitor_lg_error", "Monitor error graphically", "TSMonitorLGError", &opt));
184:   if (opt) {
185:     TSMonitorLGCtx ctx;
186:     PetscInt       howoften = 1;

188:     PetscCall(PetscOptionsInt("-ts_monitor_lg_error", "Monitor error graphically", "TSMonitorLGError", howoften, &howoften, NULL));
189:     PetscCall(TSMonitorLGCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
190:     PetscCall(TSMonitorSet(ts, TSMonitorLGError, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
191:   }
192:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_error", "View the error at each timestep", "TSMonitorError", TSMonitorError, NULL));

194:   PetscCall(PetscOptionsName("-ts_monitor_lg_timestep", "Monitor timestep size graphically", "TSMonitorLGTimeStep", &opt));
195:   if (opt) {
196:     TSMonitorLGCtx ctx;
197:     PetscInt       howoften = 1;

199:     PetscCall(PetscOptionsInt("-ts_monitor_lg_timestep", "Monitor timestep size graphically", "TSMonitorLGTimeStep", howoften, &howoften, NULL));
200:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
201:     PetscCall(TSMonitorSet(ts, TSMonitorLGTimeStep, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
202:   }
203:   PetscCall(PetscOptionsName("-ts_monitor_lg_timestep_log", "Monitor log timestep size graphically", "TSMonitorLGTimeStep", &opt));
204:   if (opt) {
205:     TSMonitorLGCtx ctx;
206:     PetscInt       howoften = 1;

208:     PetscCall(PetscOptionsInt("-ts_monitor_lg_timestep_log", "Monitor log timestep size graphically", "TSMonitorLGTimeStep", howoften, &howoften, NULL));
209:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
210:     PetscCall(TSMonitorSet(ts, TSMonitorLGTimeStep, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
211:     ctx->semilogy = PETSC_TRUE;
212:   }

214:   PetscCall(PetscOptionsName("-ts_monitor_lg_snes_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGSNESIterations", &opt));
215:   if (opt) {
216:     TSMonitorLGCtx ctx;
217:     PetscInt       howoften = 1;

219:     PetscCall(PetscOptionsInt("-ts_monitor_lg_snes_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGSNESIterations", howoften, &howoften, NULL));
220:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
221:     PetscCall(TSMonitorSet(ts, TSMonitorLGSNESIterations, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
222:   }
223:   PetscCall(PetscOptionsName("-ts_monitor_lg_ksp_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGKSPIterations", &opt));
224:   if (opt) {
225:     TSMonitorLGCtx ctx;
226:     PetscInt       howoften = 1;

228:     PetscCall(PetscOptionsInt("-ts_monitor_lg_ksp_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGKSPIterations", howoften, &howoften, NULL));
229:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
230:     PetscCall(TSMonitorSet(ts, TSMonitorLGKSPIterations, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
231:   }
232:   PetscCall(PetscOptionsName("-ts_monitor_sp_eig", "Monitor eigenvalues of linearized operator graphically", "TSMonitorSPEig", &opt));
233:   if (opt) {
234:     TSMonitorSPEigCtx ctx;
235:     PetscInt          howoften = 1;

237:     PetscCall(PetscOptionsInt("-ts_monitor_sp_eig", "Monitor eigenvalues of linearized operator graphically", "TSMonitorSPEig", howoften, &howoften, NULL));
238:     PetscCall(TSMonitorSPEigCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
239:     PetscCall(TSMonitorSet(ts, TSMonitorSPEig, ctx, (PetscCtxDestroyFn *)TSMonitorSPEigCtxDestroy));
240:   }
241:   PetscCall(PetscOptionsName("-ts_monitor_sp_swarm", "Display particle phase space from the DMSwarm", "TSMonitorSPSwarm", &opt));
242:   if (opt) {
243:     TSMonitorSPCtx ctx;
244:     PetscInt       howoften = 1, retain = 0;
245:     PetscBool      phase = PETSC_TRUE, create = PETSC_TRUE, multispecies = PETSC_FALSE;

247:     for (PetscInt i = 0; i < ts->numbermonitors; ++i)
248:       if (ts->monitor[i] == TSMonitorSPSwarmSolution) {
249:         create = PETSC_FALSE;
250:         break;
251:       }
252:     if (create) {
253:       PetscCall(PetscOptionsInt("-ts_monitor_sp_swarm", "Display particles phase space from the DMSwarm", "TSMonitorSPSwarm", howoften, &howoften, NULL));
254:       PetscCall(PetscOptionsInt("-ts_monitor_sp_swarm_retain", "Retain n points plotted to show trajectory, -1 for all points", "TSMonitorSPSwarm", retain, &retain, NULL));
255:       PetscCall(PetscOptionsBool("-ts_monitor_sp_swarm_phase", "Plot in phase space rather than coordinate space", "TSMonitorSPSwarm", phase, &phase, NULL));
256:       PetscCall(PetscOptionsBool("-ts_monitor_sp_swarm_multi_species", "Color particles by particle species", "TSMonitorSPSwarm", multispecies, &multispecies, NULL));
257:       PetscCall(TSMonitorSPCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, retain, phase, multispecies, &ctx));
258:       PetscCall(TSMonitorSet(ts, TSMonitorSPSwarmSolution, ctx, (PetscCtxDestroyFn *)TSMonitorSPCtxDestroy));
259:     }
260:   }
261:   PetscCall(PetscOptionsName("-ts_monitor_hg_swarm", "Display particle histogram from the DMSwarm", "TSMonitorHGSwarm", &opt));
262:   if (opt) {
263:     TSMonitorHGCtx ctx;
264:     PetscInt       howoften = 1, Ns = 1;
265:     PetscBool      velocity = PETSC_FALSE, create = PETSC_TRUE;

267:     for (PetscInt i = 0; i < ts->numbermonitors; ++i)
268:       if (ts->monitor[i] == TSMonitorHGSwarmSolution) {
269:         create = PETSC_FALSE;
270:         break;
271:       }
272:     if (create) {
273:       DM       sw, dm;
274:       PetscInt Nc, Nb;

276:       PetscCall(TSGetDM(ts, &sw));
277:       PetscCall(DMSwarmGetCellDM(sw, &dm));
278:       PetscCall(DMPlexGetHeightStratum(dm, 0, NULL, &Nc));
279:       Nb = PetscMin(20, PetscMax(10, Nc));
280:       PetscCall(PetscOptionsInt("-ts_monitor_hg_swarm", "Display particles histogram from the DMSwarm", "TSMonitorHGSwarm", howoften, &howoften, NULL));
281:       PetscCall(PetscOptionsBool("-ts_monitor_hg_swarm_velocity", "Plot in velocity space rather than coordinate space", "TSMonitorHGSwarm", velocity, &velocity, NULL));
282:       PetscCall(PetscOptionsInt("-ts_monitor_hg_swarm_species", "Number of species to histogram", "TSMonitorHGSwarm", Ns, &Ns, NULL));
283:       PetscCall(PetscOptionsInt("-ts_monitor_hg_swarm_bins", "Number of histogram bins", "TSMonitorHGSwarm", Nb, &Nb, NULL));
284:       PetscCall(TSMonitorHGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, Ns, Nb, velocity, &ctx));
285:       PetscCall(TSMonitorSet(ts, TSMonitorHGSwarmSolution, ctx, (PetscCtxDestroyFn *)TSMonitorHGCtxDestroy));
286:     }
287:   }
288:   opt = PETSC_FALSE;
289:   PetscCall(PetscOptionsName("-ts_monitor_draw_solution", "Monitor solution graphically", "TSMonitorDrawSolution", &opt));
290:   if (opt) {
291:     TSMonitorDrawCtx ctx;
292:     PetscInt         howoften = 1;

294:     PetscCall(PetscOptionsInt("-ts_monitor_draw_solution", "Monitor solution graphically", "TSMonitorDrawSolution", howoften, &howoften, NULL));
295:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Computed Solution", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
296:     PetscCall(TSMonitorSet(ts, TSMonitorDrawSolution, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
297:   }
298:   opt = PETSC_FALSE;
299:   PetscCall(PetscOptionsName("-ts_monitor_draw_solution_phase", "Monitor solution graphically", "TSMonitorDrawSolutionPhase", &opt));
300:   if (opt) {
301:     TSMonitorDrawCtx ctx;
302:     PetscReal        bounds[4];
303:     PetscInt         n = 4;
304:     PetscDraw        draw;
305:     PetscDrawAxis    axis;

307:     PetscCall(PetscOptionsRealArray("-ts_monitor_draw_solution_phase", "Monitor solution graphically", "TSMonitorDrawSolutionPhase", bounds, &n, NULL));
308:     PetscCheck(n == 4, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Must provide bounding box of phase field");
309:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, 1, &ctx));
310:     PetscCall(PetscViewerDrawGetDraw(ctx->viewer, 0, &draw));
311:     PetscCall(PetscViewerDrawGetDrawAxis(ctx->viewer, 0, &axis));
312:     PetscCall(PetscDrawAxisSetLimits(axis, bounds[0], bounds[2], bounds[1], bounds[3]));
313:     PetscCall(PetscDrawAxisSetLabels(axis, "Phase Diagram", "Variable 1", "Variable 2"));
314:     PetscCall(TSMonitorSet(ts, TSMonitorDrawSolutionPhase, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
315:   }
316:   opt = PETSC_FALSE;
317:   PetscCall(PetscOptionsName("-ts_monitor_draw_error", "Monitor error graphically", "TSMonitorDrawError", &opt));
318:   if (opt) {
319:     TSMonitorDrawCtx ctx;
320:     PetscInt         howoften = 1;

322:     PetscCall(PetscOptionsInt("-ts_monitor_draw_error", "Monitor error graphically", "TSMonitorDrawError", howoften, &howoften, NULL));
323:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Error", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
324:     PetscCall(TSMonitorSet(ts, TSMonitorDrawError, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
325:   }
326:   opt = PETSC_FALSE;
327:   PetscCall(PetscOptionsName("-ts_monitor_draw_solution_function", "Monitor solution provided by TSMonitorSetSolutionFunction() graphically", "TSMonitorDrawSolutionFunction", &opt));
328:   if (opt) {
329:     TSMonitorDrawCtx ctx;
330:     PetscInt         howoften = 1;

332:     PetscCall(PetscOptionsInt("-ts_monitor_draw_solution_function", "Monitor solution provided by TSMonitorSetSolutionFunction() graphically", "TSMonitorDrawSolutionFunction", howoften, &howoften, NULL));
333:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Solution provided by user function", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
334:     PetscCall(TSMonitorSet(ts, TSMonitorDrawSolutionFunction, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
335:   }

337:   opt = PETSC_FALSE;
338:   PetscCall(PetscOptionsString("-ts_monitor_solution_vtk", "Save each time step to a binary file, use filename-%%03" PetscInt_FMT ".vts", "TSMonitorSolutionVTK", NULL, monfilename, sizeof(monfilename), &flg));
339:   if (flg) {
340:     TSMonitorVTKCtx ctx;

342:     PetscCall(TSMonitorSolutionVTKCtxCreate(monfilename, &ctx));
343:     PetscCall(PetscOptionsInt("-ts_monitor_solution_vtk_interval", "Save every interval time step (-1 for last step only)", NULL, ctx->interval, &ctx->interval, NULL));
344:     PetscCall(TSMonitorSet(ts, (PetscErrorCode (*)(TS, PetscInt, PetscReal, Vec, PetscCtx))TSMonitorSolutionVTK, ctx, (PetscCtxDestroyFn *)TSMonitorSolutionVTKDestroy));
345:   }

347:   PetscCall(PetscOptionsString("-ts_monitor_dmda_ray", "Display a ray of the solution", "None", "y=0", dir, sizeof(dir), &flg));
348:   if (flg) {
349:     TSMonitorDMDARayCtx *rayctx;
350:     int                  ray = 0;
351:     DMDirection          ddir;
352:     DM                   da;
353:     PetscMPIInt          rank;

355:     PetscCheck(dir[1] == '=', PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray %s", dir);
356:     if (dir[0] == 'x') ddir = DM_X;
357:     else if (dir[0] == 'y') ddir = DM_Y;
358:     else SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray %s", dir);
359:     sscanf(dir + 2, "%d", &ray);

361:     PetscCall(PetscInfo(ts, "Displaying DMDA ray %c = %d\n", dir[0], ray));
362:     PetscCall(PetscNew(&rayctx));
363:     PetscCall(TSGetDM(ts, &da));
364:     PetscCall(DMDAGetRay(da, ddir, ray, &rayctx->ray, &rayctx->scatter));
365:     PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)ts), &rank));
366:     if (rank == 0) PetscCall(PetscViewerDrawOpen(PETSC_COMM_SELF, NULL, NULL, 0, 0, 600, 300, &rayctx->viewer));
367:     rayctx->lgctx = NULL;
368:     PetscCall(TSMonitorSet(ts, TSMonitorDMDARay, rayctx, TSMonitorDMDARayDestroy));
369:   }
370:   PetscCall(PetscOptionsString("-ts_monitor_lg_dmda_ray", "Display a ray of the solution", "None", "x=0", dir, sizeof(dir), &flg));
371:   if (flg) {
372:     TSMonitorDMDARayCtx *rayctx;
373:     int                  ray = 0;
374:     DMDirection          ddir;
375:     DM                   da;
376:     PetscInt             howoften = 1;

378:     PetscCheck(dir[1] == '=', PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Malformed ray %s", dir);
379:     if (dir[0] == 'x') ddir = DM_X;
380:     else if (dir[0] == 'y') ddir = DM_Y;
381:     else SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray direction %s", dir);
382:     sscanf(dir + 2, "%d", &ray);

384:     PetscCall(PetscInfo(ts, "Displaying LG DMDA ray %c = %d\n", dir[0], ray));
385:     PetscCall(PetscNew(&rayctx));
386:     PetscCall(TSGetDM(ts, &da));
387:     PetscCall(DMDAGetRay(da, ddir, ray, &rayctx->ray, &rayctx->scatter));
388:     PetscCall(TSMonitorLGCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 600, 400, howoften, &rayctx->lgctx));
389:     PetscCall(TSMonitorSet(ts, TSMonitorLGDMDARay, rayctx, TSMonitorDMDARayDestroy));
390:   }

392:   PetscCall(PetscOptionsName("-ts_monitor_envelope", "Monitor maximum and minimum value of each component of the solution", "TSMonitorEnvelope", &opt));
393:   if (opt) {
394:     TSMonitorEnvelopeCtx ctx;

396:     PetscCall(TSMonitorEnvelopeCtxCreate(ts, &ctx));
397:     PetscCall(TSMonitorSet(ts, TSMonitorEnvelope, ctx, (PetscCtxDestroyFn *)TSMonitorEnvelopeCtxDestroy));
398:   }
399:   flg = PETSC_FALSE;
400:   PetscCall(PetscOptionsBool("-ts_monitor_cancel", "Remove all monitors", "TSMonitorCancel", flg, &flg, &opt));
401:   if (opt && flg) PetscCall(TSMonitorCancel(ts));

403:   flg = PETSC_FALSE;
404:   PetscCall(PetscOptionsBool("-ts_fd_color", "Use finite differences with coloring to compute IJacobian", "TSComputeIJacobianDefaultColor", flg, &flg, NULL));
405:   if (flg) {
406:     DM dm;

408:     PetscCall(TSGetDM(ts, &dm));
409:     PetscCall(DMTSUnsetIJacobianContext_Internal(dm));
410:     PetscCall(TSSetIJacobian(ts, NULL, NULL, TSComputeIJacobianDefaultColor, NULL));
411:     PetscCall(PetscInfo(ts, "Setting default finite difference coloring Jacobian matrix\n"));
412:   }

414:   /* Handle specific TS options */
415:   PetscTryTypeMethod(ts, setfromoptions, PetscOptionsObject);

417:   /* Handle TSAdapt options */
418:   PetscCall(TSGetAdapt(ts, &ts->adapt));
419:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));
420:   PetscCall(TSAdaptSetFromOptions(ts->adapt, PetscOptionsObject));

422:   /* TS trajectory must be set after TS, since it may use some TS options above */
423:   tflg = ts->trajectory ? PETSC_TRUE : PETSC_FALSE;
424:   PetscCall(PetscOptionsBool("-ts_save_trajectory", "Save the solution at each timestep", "TSSetSaveTrajectory", tflg, &tflg, NULL));
425:   if (tflg) PetscCall(TSSetSaveTrajectory(ts));

427:   PetscCall(TSAdjointSetFromOptions(ts, PetscOptionsObject));

429:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
430:   PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)ts, PetscOptionsObject));
431:   PetscOptionsEnd();

433:   if (ts->trajectory) PetscCall(TSTrajectorySetFromOptions(ts->trajectory, ts));

435:   /* why do we have to do this here and not during TSSetUp? */
436:   PetscCall(TSGetSNES(ts, &ts->snes));
437:   if (ts->problem_type == TS_LINEAR) {
438:     PetscCall(PetscObjectTypeCompareAny((PetscObject)ts->snes, &flg, SNESKSPONLY, SNESKSPTRANSPOSEONLY, ""));
439:     if (!flg) PetscCall(SNESSetType(ts->snes, SNESKSPONLY));
440:   }
441:   PetscCall(SNESSetFromOptions(ts->snes));
442:   PetscFunctionReturn(PETSC_SUCCESS);
443: }

445: /*@
446:   TSGetTrajectory - Gets the trajectory from a `TS` if it exists

448:   Collective

450:   Input Parameter:
451: . ts - the `TS` context obtained from `TSCreate()`

453:   Output Parameter:
454: . tr - the `TSTrajectory` object, if it exists

456:   Level: advanced

458:   Note:
459:   This routine should be called after all `TS` options have been set

461: .seealso: [](ch_ts), `TS`, `TSTrajectory`, `TSAdjointSolve()`, `TSTrajectoryCreate()`
462: @*/
463: PetscErrorCode TSGetTrajectory(TS ts, TSTrajectory *tr)
464: {
465:   PetscFunctionBegin;
467:   *tr = ts->trajectory;
468:   PetscFunctionReturn(PETSC_SUCCESS);
469: }

471: /*@
472:   TSSetSaveTrajectory - Causes the `TS` to save its solutions as it iterates forward in time in a `TSTrajectory` object

474:   Collective

476:   Input Parameter:
477: . ts - the `TS` context obtained from `TSCreate()`

479:   Options Database Keys:
480: + -ts_save_trajectory                                         - saves the trajectory to a file
481: - -ts_trajectory_type (basic|singlefile|memory|visualization) - set trajectory type

483:   Level: intermediate

485:   Notes:
486:   This routine should be called after all `TS` options have been set

488:   The `TSTRAJECTORYVISUALIZATION` files can be loaded into Python with $PETSC_DIR/lib/petsc/bin/PetscBinaryIOTrajectory.py and
489:   MATLAB with $PETSC_DIR/share/petsc/matlab/PetscReadBinaryTrajectory.m

491: .seealso: [](ch_ts), `TS`, `TSTrajectoryType`, `TSTrajectory`, `TSGetTrajectory()`, `TSAdjointSolve()`
492: @*/
493: PetscErrorCode TSSetSaveTrajectory(TS ts)
494: {
495:   PetscFunctionBegin;
497:   if (!ts->trajectory) PetscCall(TSTrajectoryCreate(PetscObjectComm((PetscObject)ts), &ts->trajectory));
498:   PetscFunctionReturn(PETSC_SUCCESS);
499: }

501: /*@
502:   TSResetTrajectory - Destroys and recreates the internal `TSTrajectory` object

504:   Collective

506:   Input Parameter:
507: . ts - the `TS` context obtained from `TSCreate()`

509:   Level: intermediate

511: .seealso: [](ch_ts), `TSTrajectory`, `TSGetTrajectory()`, `TSAdjointSolve()`, `TSRemoveTrajectory()`
512: @*/
513: PetscErrorCode TSResetTrajectory(TS ts)
514: {
515:   PetscFunctionBegin;
517:   if (ts->trajectory) {
518:     PetscCall(TSTrajectoryDestroy(&ts->trajectory));
519:     PetscCall(TSTrajectoryCreate(PetscObjectComm((PetscObject)ts), &ts->trajectory));
520:   }
521:   PetscFunctionReturn(PETSC_SUCCESS);
522: }

524: /*@
525:   TSRemoveTrajectory - Destroys and removes the internal `TSTrajectory` object from a `TS`

527:   Collective

529:   Input Parameter:
530: . ts - the `TS` context obtained from `TSCreate()`

532:   Level: intermediate

534: .seealso: [](ch_ts), `TSTrajectory`, `TSResetTrajectory()`, `TSAdjointSolve()`
535: @*/
536: PetscErrorCode TSRemoveTrajectory(TS ts)
537: {
538:   PetscFunctionBegin;
540:   PetscCall(TSTrajectoryDestroy(&ts->trajectory));
541:   PetscFunctionReturn(PETSC_SUCCESS);
542: }

544: /*@
545:   TSComputeRHSJacobian - Computes the Jacobian matrix that has been
546:   set with `TSSetRHSJacobian()`.

548:   Collective

550:   Input Parameters:
551: + ts - the `TS` context
552: . t  - current timestep
553: - U  - input vector

555:   Output Parameters:
556: + A - Jacobian matrix
557: - B - optional matrix used to compute the preconditioner, often the same as `A`

559:   Level: developer

561:   Note:
562:   Most users should not need to explicitly call this routine, as it
563:   is used internally within the ODE integrators.

565: .seealso: [](ch_ts), `TS`, `TSSetRHSJacobian()`, `KSPSetOperators()`
566: @*/
567: PetscErrorCode TSComputeRHSJacobian(TS ts, PetscReal t, Vec U, Mat A, Mat B)
568: {
569:   PetscObjectState Ustate;
570:   PetscObjectId    Uid;
571:   DM               dm;
572:   DMTS             tsdm;
573:   TSRHSJacobianFn *rhsjacobianfunc;
574:   void            *ctx;
575:   TSRHSFunctionFn *rhsfunction;

577:   PetscFunctionBegin;
580:   PetscCheckSameComm(ts, 1, U, 3);
581:   PetscCall(TSGetDM(ts, &dm));
582:   PetscCall(DMGetDMTS(dm, &tsdm));
583:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));
584:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobianfunc, &ctx));
585:   PetscCall(PetscObjectStateGet((PetscObject)U, &Ustate));
586:   PetscCall(PetscObjectGetId((PetscObject)U, &Uid));

588:   if (ts->rhsjacobian.time == t && (ts->problem_type == TS_LINEAR || (ts->rhsjacobian.Xid == Uid && ts->rhsjacobian.Xstate == Ustate)) && (rhsfunction != TSComputeRHSFunctionLinear)) PetscFunctionReturn(PETSC_SUCCESS);

590:   PetscCheck(ts->rhsjacobian.shift == 0.0 || !ts->rhsjacobian.reuse, PetscObjectComm((PetscObject)ts), PETSC_ERR_USER, "Should not call TSComputeRHSJacobian() on a shifted matrix (shift=%lf) when RHSJacobian is reusable.", (double)ts->rhsjacobian.shift);
591:   if (rhsjacobianfunc) {
592:     PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, A, B));
593:     PetscCallBack("TS callback Jacobian", (*rhsjacobianfunc)(ts, t, U, A, B, ctx));
594:     ts->rhsjacs++;
595:     PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, A, B));
596:   } else {
597:     PetscCall(MatZeroEntries(A));
598:     if (B && A != B) PetscCall(MatZeroEntries(B));
599:   }
600:   ts->rhsjacobian.time  = t;
601:   ts->rhsjacobian.shift = 0;
602:   ts->rhsjacobian.scale = 1.;
603:   PetscCall(PetscObjectGetId((PetscObject)U, &ts->rhsjacobian.Xid));
604:   PetscCall(PetscObjectStateGet((PetscObject)U, &ts->rhsjacobian.Xstate));
605:   PetscFunctionReturn(PETSC_SUCCESS);
606: }

608: /*@
609:   TSComputeRHSFunction - Evaluates the right-hand-side function for a `TS`

611:   Collective

613:   Input Parameters:
614: + ts - the `TS` context
615: . t  - current time
616: - U  - state vector

618:   Output Parameter:
619: . y - right-hand side

621:   Level: developer

623:   Note:
624:   Most users should not need to explicitly call this routine, as it
625:   is used internally within the nonlinear solvers.

627: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSComputeIFunction()`
628: @*/
629: PetscErrorCode TSComputeRHSFunction(TS ts, PetscReal t, Vec U, Vec y)
630: {
631:   TSRHSFunctionFn *rhsfunction;
632:   TSIFunctionFn   *ifunction;
633:   void            *ctx;
634:   DM               dm;

636:   PetscFunctionBegin;
640:   PetscCall(TSGetDM(ts, &dm));
641:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, &ctx));
642:   PetscCall(DMTSGetIFunction(dm, &ifunction, NULL));

644:   PetscCheck(rhsfunction || ifunction, PetscObjectComm((PetscObject)ts), PETSC_ERR_USER, "Must call TSSetRHSFunction() and / or TSSetIFunction()");

646:   if (rhsfunction) {
647:     PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, y, 0));
648:     PetscCall(VecLockReadPush(U));
649:     PetscCallBack("TS callback right-hand-side", (*rhsfunction)(ts, t, U, y, ctx));
650:     PetscCall(VecLockReadPop(U));
651:     ts->rhsfuncs++;
652:     PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, y, 0));
653:   } else PetscCall(VecZeroEntries(y));
654:   PetscFunctionReturn(PETSC_SUCCESS);
655: }

657: /*@
658:   TSComputeSolutionFunction - Evaluates the solution function.

660:   Collective

662:   Input Parameters:
663: + ts - the `TS` context
664: - t  - current time

666:   Output Parameter:
667: . U - the solution

669:   Level: developer

671: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSSetRHSFunction()`, `TSComputeIFunction()`
672: @*/
673: PetscErrorCode TSComputeSolutionFunction(TS ts, PetscReal t, Vec U)
674: {
675:   TSSolutionFn *solutionfunction;
676:   void         *ctx;
677:   DM            dm;

679:   PetscFunctionBegin;
682:   PetscCall(TSGetDM(ts, &dm));
683:   PetscCall(DMTSGetSolutionFunction(dm, &solutionfunction, &ctx));
684:   if (solutionfunction) PetscCallBack("TS callback solution", (*solutionfunction)(ts, t, U, ctx));
685:   PetscFunctionReturn(PETSC_SUCCESS);
686: }
687: /*@
688:   TSComputeForcingFunction - Evaluates the forcing function.

690:   Collective

692:   Input Parameters:
693: + ts - the `TS` context
694: - t  - current time

696:   Output Parameter:
697: . U - the function value

699:   Level: developer

701: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSSetRHSFunction()`, `TSComputeIFunction()`
702: @*/
703: PetscErrorCode TSComputeForcingFunction(TS ts, PetscReal t, Vec U)
704: {
705:   void        *ctx;
706:   DM           dm;
707:   TSForcingFn *forcing;

709:   PetscFunctionBegin;
712:   PetscCall(TSGetDM(ts, &dm));
713:   PetscCall(DMTSGetForcingFunction(dm, &forcing, &ctx));

715:   if (forcing) PetscCallBack("TS callback forcing function", (*forcing)(ts, t, U, ctx));
716:   PetscFunctionReturn(PETSC_SUCCESS);
717: }

719: PetscErrorCode TSGetRHSMats_Private(TS ts, Mat *Arhs, Mat *Brhs)
720: {
721:   Mat            A, B;
722:   TSIJacobianFn *ijacobian;

724:   PetscFunctionBegin;
725:   if (Arhs) *Arhs = NULL;
726:   if (Brhs) *Brhs = NULL;
727:   PetscCall(TSGetIJacobian(ts, &A, &B, &ijacobian, NULL));
728:   if (Arhs) {
729:     if (!ts->Arhs) {
730:       if (ijacobian) {
731:         PetscCall(MatDuplicate(A, MAT_DO_NOT_COPY_VALUES, &ts->Arhs));
732:         PetscCall(TSSetMatStructure(ts, SAME_NONZERO_PATTERN));
733:       } else {
734:         ts->Arhs = A;
735:         PetscCall(PetscObjectReference((PetscObject)A));
736:       }
737:     } else {
738:       PetscBool flg;
739:       PetscCall(SNESGetUseMatrixFree(ts->snes, NULL, &flg));
740:       /* Handle case where user provided only RHSJacobian and used -snes_mf_operator */
741:       if (flg && !ijacobian && ts->Arhs == ts->Brhs) {
742:         PetscCall(PetscObjectDereference((PetscObject)ts->Arhs));
743:         ts->Arhs = A;
744:         PetscCall(PetscObjectReference((PetscObject)A));
745:       }
746:     }
747:     *Arhs = ts->Arhs;
748:   }
749:   if (Brhs) {
750:     if (!ts->Brhs) {
751:       if (A != B) {
752:         if (ijacobian) {
753:           PetscCall(MatDuplicate(B, MAT_DO_NOT_COPY_VALUES, &ts->Brhs));
754:         } else {
755:           ts->Brhs = B;
756:           PetscCall(PetscObjectReference((PetscObject)B));
757:         }
758:       } else {
759:         PetscCall(PetscObjectReference((PetscObject)ts->Arhs));
760:         ts->Brhs = ts->Arhs;
761:       }
762:     }
763:     *Brhs = ts->Brhs;
764:   }
765:   PetscFunctionReturn(PETSC_SUCCESS);
766: }

768: /*@
769:   TSComputeIFunction - Evaluates the DAE residual written in the implicit form F(t,U,Udot)=0

771:   Collective

773:   Input Parameters:
774: + ts   - the `TS` context
775: . t    - current time
776: . U    - state vector
777: . Udot - time derivative of state vector
778: - imex - flag indicates if the method is `TSARKIMEX` so that the RHSFunction should be kept separate

780:   Output Parameter:
781: . Y - right-hand side

783:   Level: developer

785:   Note:
786:   Most users should not need to explicitly call this routine, as it
787:   is used internally within the nonlinear solvers.

789:   If the user did not write their equations in implicit form, this
790:   function recasts them in implicit form.

792: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `TSComputeRHSFunction()`
793: @*/
794: PetscErrorCode TSComputeIFunction(TS ts, PetscReal t, Vec U, Vec Udot, Vec Y, PetscBool imex)
795: {
796:   TSIFunctionFn   *ifunction;
797:   TSRHSFunctionFn *rhsfunction;
798:   void            *ctx;
799:   DM               dm;

801:   PetscFunctionBegin;

807:   PetscCall(TSGetDM(ts, &dm));
808:   PetscCall(DMTSGetIFunction(dm, &ifunction, &ctx));
809:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));

811:   PetscCheck(rhsfunction || ifunction, PetscObjectComm((PetscObject)ts), PETSC_ERR_USER, "Must call TSSetRHSFunction() and / or TSSetIFunction()");

813:   PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, Udot, Y));
814:   if (ifunction) {
815:     PetscCallBack("TS callback implicit function", (*ifunction)(ts, t, U, Udot, Y, ctx));
816:     ts->ifuncs++;
817:   }
818:   if (imex) {
819:     if (!ifunction) PetscCall(VecCopy(Udot, Y));
820:   } else if (rhsfunction) {
821:     if (ifunction) {
822:       Vec Frhs;

824:       PetscCall(DMGetGlobalVector(dm, &Frhs));
825:       PetscCall(TSComputeRHSFunction(ts, t, U, Frhs));
826:       PetscCall(VecAXPY(Y, -1, Frhs));
827:       PetscCall(DMRestoreGlobalVector(dm, &Frhs));
828:     } else {
829:       PetscCall(TSComputeRHSFunction(ts, t, U, Y));
830:       PetscCall(VecAYPX(Y, -1, Udot));
831:     }
832:   }
833:   PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, Udot, Y));
834:   PetscFunctionReturn(PETSC_SUCCESS);
835: }

837: /*
838:    TSRecoverRHSJacobian - Recover the Jacobian matrix so that one can call `TSComputeRHSJacobian()` on it.

840:    Note:
841:    This routine is needed when one switches from `TSComputeIJacobian()` to `TSComputeRHSJacobian()` because the Jacobian matrix may be shifted or scaled in `TSComputeIJacobian()`.

843: */
844: static PetscErrorCode TSRecoverRHSJacobian(TS ts, Mat A, Mat B)
845: {
846:   PetscFunctionBegin;
848:   PetscCheck(A == ts->Arhs, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Invalid Amat");
849:   PetscCheck(B == ts->Brhs, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Invalid Bmat");

851:   if (ts->rhsjacobian.shift) PetscCall(MatShift(A, -ts->rhsjacobian.shift));
852:   if (ts->rhsjacobian.scale == -1.) PetscCall(MatScale(A, -1));
853:   if (B && B == ts->Brhs && A != B) {
854:     if (ts->rhsjacobian.shift) PetscCall(MatShift(B, -ts->rhsjacobian.shift));
855:     if (ts->rhsjacobian.scale == -1.) PetscCall(MatScale(B, -1));
856:   }
857:   ts->rhsjacobian.shift = 0;
858:   ts->rhsjacobian.scale = 1.;
859:   PetscFunctionReturn(PETSC_SUCCESS);
860: }

862: /*
863:   TSComputeIJacobian_Internal - Evaluates the Jacobian of the DAE

865:   Collective

867:   Input Parameters:
868: + ts          - the `TS` context
869: . ijacobian   - function to compute LHS Jacobian
870: . rhsjacobian - function to compute RHS Jacobian
871: . ctx         - user context for Jacobian functions
872: . t           - current timestep
873: . U           - state vector
874: . Udot        - time derivative of state vector
875: . shift       - shift to apply, see note below
876: - imex        - flag indicates if the method is `TSARKIMEX` so that the RHSJacobian should be kept separate

878:   Output Parameters:
879: + A - Jacobian matrix
880: - B - matrix from which the preconditioner is constructed; often the same as `A`

882:   Level: developer

884:   Notes:
885:   This function exists so that a user can assemble the Jacobian pieces with functions not stores in the `DMTS`. This was necessary in `TSDISCGRAD` since two different representations of the formulation can be stored.

887:   If $ F(t,U,\dot{U})=0 $ is the DAE, the required Jacobian is
888: .vb
889:    dF/dU + shift*dF/dUdot
890: .ve

892: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`
893: */
894: PetscErrorCode TSComputeIJacobian_Internal(TS ts, TSIJacobianFn *ijacobian, TSRHSJacobianFn *rhsjacobian, void *ctx, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, PetscBool imex)
895: {
896:   PetscFunctionBegin;
897:   PetscCheck(rhsjacobian || ijacobian, PetscObjectComm((PetscObject)ts), PETSC_ERR_USER, "Must call TSSetRHSJacobian() and / or TSSetIJacobian()");

899:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, A, B));
900:   if (ijacobian) {
901:     PetscCallBack("TS callback implicit Jacobian", (*ijacobian)(ts, t, U, Udot, shift, A, B, ctx));
902:     ts->ijacs++;
903:   }
904:   if (imex) {
905:     if (!ijacobian) { /* system was written as Udot = G(t,U) */
906:       PetscBool assembled;
907:       if (rhsjacobian) {
908:         Mat Arhs = NULL;
909:         PetscCall(TSGetRHSMats_Private(ts, &Arhs, NULL));
910:         if (A == Arhs) {
911:           PetscCheck(rhsjacobian != TSComputeRHSJacobianConstant, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Unsupported operation! cannot use TSComputeRHSJacobianConstant"); /* there is no way to reconstruct shift*M-J since J cannot be reevaluated */
912:           ts->rhsjacobian.time = PETSC_MIN_REAL;
913:         }
914:       }
915:       PetscCall(MatZeroEntries(A));
916:       PetscCall(MatAssembled(A, &assembled));
917:       if (!assembled) {
918:         PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
919:         PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
920:       }
921:       PetscCall(MatShift(A, shift));
922:       if (A != B) {
923:         PetscCall(MatZeroEntries(B));
924:         PetscCall(MatAssembled(B, &assembled));
925:         if (!assembled) {
926:           PetscCall(MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY));
927:           PetscCall(MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY));
928:         }
929:         PetscCall(MatShift(B, shift));
930:       }
931:     }
932:   } else {
933:     Mat Arhs = NULL, Brhs = NULL;

935:     /* RHSJacobian needs to be converted to part of IJacobian if exists */
936:     if (rhsjacobian) PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
937:     if (Arhs == A) { /* No IJacobian matrix, so we only have the RHS matrix */
938:       DM               dm;
939:       PetscObjectState Ustate;
940:       PetscObjectId    Uid;
941:       TSRHSFunctionFn *rhsfunction;

943:       PetscCall(TSGetDM(ts, &dm));
944:       PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));
945:       PetscCall(PetscObjectStateGet((PetscObject)U, &Ustate));
946:       PetscCall(PetscObjectGetId((PetscObject)U, &Uid));
947:       if ((rhsjacobian == TSComputeRHSJacobianConstant || (ts->rhsjacobian.time == t && (ts->problem_type == TS_LINEAR || (ts->rhsjacobian.Xid == Uid && ts->rhsjacobian.Xstate == Ustate)) && rhsfunction != TSComputeRHSFunctionLinear)) &&
948:           ts->rhsjacobian.scale == -1.) {                      /* No need to recompute RHSJacobian */
949:         PetscCall(MatShift(A, shift - ts->rhsjacobian.shift)); /* revert the old shift and add the new shift with a single call to MatShift */
950:         if (A != B) PetscCall(MatShift(B, shift - ts->rhsjacobian.shift));
951:       } else {
952:         PetscBool flg;

954:         if (ts->rhsjacobian.reuse) { /* Undo the damage */
955:           /* MatScale has a short path for this case.
956:              However, this code path is taken the first time TSComputeRHSJacobian is called
957:              and the matrices have not been assembled yet */
958:           PetscCall(TSRecoverRHSJacobian(ts, A, B));
959:         }
960:         PetscCall(TSComputeRHSJacobian(ts, t, U, A, B));
961:         PetscCall(SNESGetUseMatrixFree(ts->snes, NULL, &flg));
962:         /* since -snes_mf_operator uses the full SNES function it does not need to be shifted or scaled here */
963:         if (!flg) {
964:           PetscCall(MatScale(A, -1));
965:           PetscCall(MatShift(A, shift));
966:         }
967:         if (A != B) {
968:           PetscCall(MatScale(B, -1));
969:           PetscCall(MatShift(B, shift));
970:         }
971:       }
972:       ts->rhsjacobian.scale = -1;
973:       ts->rhsjacobian.shift = shift;
974:     } else if (Arhs) {  /* Both IJacobian and RHSJacobian */
975:       if (!ijacobian) { /* No IJacobian provided, but we have a separate RHS matrix */
976:         PetscCall(MatZeroEntries(A));
977:         PetscCall(MatShift(A, shift));
978:         if (A != B) {
979:           PetscCall(MatZeroEntries(B));
980:           PetscCall(MatShift(B, shift));
981:         }
982:       }
983:       PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
984:       PetscCall(MatAXPY(A, -1, Arhs, ts->axpy_pattern));
985:       if (A != B) PetscCall(MatAXPY(B, -1, Brhs, ts->axpy_pattern));
986:     }
987:   }
988:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, A, B));
989:   PetscFunctionReturn(PETSC_SUCCESS);
990: }

992: /*@
993:   TSComputeIJacobian - Evaluates the Jacobian of the DAE

995:   Collective

997:   Input Parameters:
998: + ts    - the `TS` context
999: . t     - current timestep
1000: . U     - state vector
1001: . Udot  - time derivative of state vector
1002: . shift - shift to apply, see note below
1003: - imex  - flag indicates if the method is `TSARKIMEX` so that the RHSJacobian should be kept separate

1005:   Output Parameters:
1006: + A - Jacobian matrix
1007: - B - matrix from which the preconditioner is constructed; often the same as `A`

1009:   Level: developer

1011:   Notes:
1012:   If $ F(t,U,\dot{U})=0 $ is the DAE, the required Jacobian is
1013: .vb
1014:    dF/dU + shift*dF/dUdot
1015: .ve
1016:   Most users should not need to explicitly call this routine, as it
1017:   is used internally within the nonlinear solvers.

1019: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`
1020: @*/
1021: PetscErrorCode TSComputeIJacobian(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, PetscBool imex)
1022: {
1023:   TSIJacobianFn   *ijacobian;
1024:   TSRHSJacobianFn *rhsjacobian;
1025:   DM               dm;
1026:   void            *ctx;

1028:   PetscFunctionBegin;

1035:   PetscCall(TSGetDM(ts, &dm));
1036:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, &ctx));
1037:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));
1038:   PetscCall(TSComputeIJacobian_Internal(ts, ijacobian, rhsjacobian, ctx, t, U, Udot, shift, A, B, imex));
1039:   PetscFunctionReturn(PETSC_SUCCESS);
1040: }

1042: /*@
1043:   TSSetRHSFunction - Sets the routine for evaluating the function,
1044:   where U_t = G(t,u).

1046:   Logically Collective

1048:   Input Parameters:
1049: + ts  - the `TS` context obtained from `TSCreate()`
1050: . r   - vector to put the computed right-hand side (or `NULL` to have it created)
1051: . f   - routine for evaluating the right-hand-side function
1052: - ctx - [optional] user-defined context for private data for the function evaluation routine (may be `NULL`)

1054:   Level: beginner

1056:   Note:
1057:   You must call this function or `TSSetIFunction()` to define your ODE. You cannot use this function when solving a DAE.

1059: .seealso: [](ch_ts), `TS`, `TSRHSFunctionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSSetIFunction()`
1060: @*/
1061: PetscErrorCode TSSetRHSFunction(TS ts, Vec r, TSRHSFunctionFn *f, PetscCtx ctx)
1062: {
1063:   SNES snes;
1064:   Vec  ralloc = NULL;
1065:   DM   dm;

1067:   PetscFunctionBegin;

1071:   PetscCall(TSGetDM(ts, &dm));
1072:   PetscCall(DMTSSetRHSFunction(dm, f, ctx));
1073:   PetscCall(TSGetSNES(ts, &snes));
1074:   if (!r && !ts->dm && ts->vec_sol) {
1075:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1076:     r = ralloc;
1077:   }
1078:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1079:   PetscCall(VecDestroy(&ralloc));
1080:   PetscFunctionReturn(PETSC_SUCCESS);
1081: }

1083: /*@
1084:   TSSetSolutionFunction - Provide a function that computes the solution of the ODE or DAE

1086:   Logically Collective

1088:   Input Parameters:
1089: + ts  - the `TS` context obtained from `TSCreate()`
1090: . f   - routine for evaluating the solution
1091: - ctx - [optional] user-defined context for private data for the
1092:           function evaluation routine (may be `NULL`)

1094:   Options Database Keys:
1095: + -ts_monitor_lg_error   - create a graphical monitor of error history, requires user to have provided `TSSetSolutionFunction()`
1096: - -ts_monitor_draw_error - Monitor error graphically, requires user to have provided `TSSetSolutionFunction()`

1098:   Level: intermediate

1100:   Notes:
1101:   This routine is used for testing accuracy of time integration schemes when you already know the solution.
1102:   If analytic solutions are not known for your system, consider using the Method of Manufactured Solutions to
1103:   create closed-form solutions with non-physical forcing terms.

1105:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1107: .seealso: [](ch_ts), `TS`, `TSSolutionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSComputeSolutionFunction()`, `TSSetForcingFunction()`, `TSSetSolution()`, `TSGetSolution()`, `TSMonitorLGError()`, `TSMonitorDrawError()`
1108: @*/
1109: PetscErrorCode TSSetSolutionFunction(TS ts, TSSolutionFn *f, PetscCtx ctx)
1110: {
1111:   DM dm;

1113:   PetscFunctionBegin;
1115:   PetscCall(TSGetDM(ts, &dm));
1116:   PetscCall(DMTSSetSolutionFunction(dm, f, ctx));
1117:   PetscFunctionReturn(PETSC_SUCCESS);
1118: }

1120: /*@
1121:   TSSetForcingFunction - Provide a function that computes a forcing term for a ODE or PDE

1123:   Logically Collective

1125:   Input Parameters:
1126: + ts   - the `TS` context obtained from `TSCreate()`
1127: . func - routine for evaluating the forcing function
1128: - ctx  - [optional] user-defined context for private data for the function evaluation routine
1129:          (may be `NULL`)

1131:   Level: intermediate

1133:   Notes:
1134:   This routine is useful for testing accuracy of time integration schemes when using the Method of Manufactured Solutions to
1135:   create closed-form solutions with a non-physical forcing term. It allows you to use the Method of Manufactored Solution without directly editing the
1136:   definition of the problem you are solving and hence possibly introducing bugs.

1138:   This replaces the ODE F(u,u_t,t) = 0 the `TS` is solving with F(u,u_t,t) - func(t) = 0

1140:   This forcing function does not depend on the solution to the equations, it can only depend on spatial location, time, and possibly parameters, the
1141:   parameters can be passed in the ctx variable.

1143:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1145: .seealso: [](ch_ts), `TS`, `TSForcingFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`,
1146: `TSComputeSolutionFunction()`, `TSSetSolutionFunction()`
1147: @*/
1148: PetscErrorCode TSSetForcingFunction(TS ts, TSForcingFn *func, PetscCtx ctx)
1149: {
1150:   DM dm;

1152:   PetscFunctionBegin;
1154:   PetscCall(TSGetDM(ts, &dm));
1155:   PetscCall(DMTSSetForcingFunction(dm, func, ctx));
1156:   PetscFunctionReturn(PETSC_SUCCESS);
1157: }

1159: /*@
1160:   TSSetRHSJacobian - Sets the function to compute the Jacobian of G,
1161:   where U_t = G(U,t), as well as the location to store the matrix.

1163:   Logically Collective

1165:   Input Parameters:
1166: + ts   - the `TS` context obtained from `TSCreate()`
1167: . Amat - (approximate) location to store Jacobian matrix entries computed by `f`
1168: . Pmat - matrix from which preconditioner is to be constructed (usually the same as `Amat`)
1169: . f    - the Jacobian evaluation routine
1170: - ctx  - [optional] user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1172:   Level: beginner

1174:   Notes:
1175:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1177:   The `TS` solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f()`
1178:   You should not assume the values are the same in the next call to f() as you set them in the previous call.

1180: .seealso: [](ch_ts), `TS`, `TSRHSJacobianFn`, `SNESComputeJacobianDefaultColor()`,
1181: `TSSetRHSFunction()`, `TSRHSJacobianSetReuse()`, `TSSetIJacobian()`, `TSRHSFunctionFn`, `TSIFunctionFn`
1182: @*/
1183: PetscErrorCode TSSetRHSJacobian(TS ts, Mat Amat, Mat Pmat, TSRHSJacobianFn *f, PetscCtx ctx)
1184: {
1185:   SNES           snes;
1186:   DM             dm;
1187:   TSIJacobianFn *ijacobian;

1189:   PetscFunctionBegin;
1193:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1194:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1196:   PetscCall(TSGetDM(ts, &dm));
1197:   PetscCall(DMTSSetRHSJacobian(dm, f, ctx));
1198:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, NULL));
1199:   PetscCall(TSGetSNES(ts, &snes));
1200:   if (!ijacobian) PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1201:   if (Amat) {
1202:     PetscCall(PetscObjectReference((PetscObject)Amat));
1203:     PetscCall(MatDestroy(&ts->Arhs));
1204:     ts->Arhs = Amat;
1205:   }
1206:   if (Pmat) {
1207:     PetscCall(PetscObjectReference((PetscObject)Pmat));
1208:     PetscCall(MatDestroy(&ts->Brhs));
1209:     ts->Brhs = Pmat;
1210:   }
1211:   PetscFunctionReturn(PETSC_SUCCESS);
1212: }

1214: /*@
1215:   TSSetIFunction - Set the function to compute F(t,U,U_t) where F() = 0 is the DAE to be solved.

1217:   Logically Collective

1219:   Input Parameters:
1220: + ts  - the `TS` context obtained from `TSCreate()`
1221: . r   - vector to hold the residual (or `NULL` to have it created internally)
1222: . f   - the function evaluation routine
1223: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1225:   Level: beginner

1227:   Note:
1228:   The user MUST call either this routine or `TSSetRHSFunction()` to define the ODE.  When solving DAEs you must use this function.

1230: .seealso: [](ch_ts), `TS`, `TSIFunctionFn`, `TSSetRHSJacobian()`, `TSSetRHSFunction()`,
1231: `TSSetIJacobian()`
1232: @*/
1233: PetscErrorCode TSSetIFunction(TS ts, Vec r, TSIFunctionFn *f, PetscCtx ctx)
1234: {
1235:   SNES snes;
1236:   Vec  ralloc = NULL;
1237:   DM   dm;

1239:   PetscFunctionBegin;

1243:   PetscCall(TSGetDM(ts, &dm));
1244:   PetscCall(DMTSSetIFunction(dm, f, ctx));

1246:   PetscCall(TSGetSNES(ts, &snes));
1247:   if (!r && !ts->dm && ts->vec_sol) {
1248:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1249:     r = ralloc;
1250:   }
1251:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1252:   PetscCall(VecDestroy(&ralloc));
1253:   PetscFunctionReturn(PETSC_SUCCESS);
1254: }

1256: /*@
1257:   TSGetIFunction - Returns the vector where the implicit residual is stored and the function/context to compute it.

1259:   Not Collective

1261:   Input Parameter:
1262: . ts - the `TS` context

1264:   Output Parameters:
1265: + r    - vector to hold residual (or `NULL`)
1266: . func - the function to compute residual (or `NULL`)
1267: - ctx  - the function context (or `NULL`)

1269:   Level: advanced

1271: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`
1272: @*/
1273: PetscErrorCode TSGetIFunction(TS ts, Vec *r, TSIFunctionFn **func, PetscCtxRt ctx)
1274: {
1275:   SNES snes;
1276:   DM   dm;

1278:   PetscFunctionBegin;
1280:   PetscCall(TSGetSNES(ts, &snes));
1281:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1282:   PetscCall(TSGetDM(ts, &dm));
1283:   PetscCall(DMTSGetIFunction(dm, func, ctx));
1284:   PetscFunctionReturn(PETSC_SUCCESS);
1285: }

1287: /*@
1288:   TSGetRHSFunction - Returns the vector where the right-hand side is stored and the function/context to compute it.

1290:   Not Collective

1292:   Input Parameter:
1293: . ts - the `TS` context

1295:   Output Parameters:
1296: + r    - vector to hold computed right-hand side (or `NULL`)
1297: . func - the function to compute right-hand side (or `NULL`)
1298: - ctx  - the function context (or `NULL`)

1300:   Level: advanced

1302: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `SNESGetFunction()`
1303: @*/
1304: PetscErrorCode TSGetRHSFunction(TS ts, Vec *r, TSRHSFunctionFn **func, PetscCtxRt ctx)
1305: {
1306:   SNES snes;
1307:   DM   dm;

1309:   PetscFunctionBegin;
1311:   PetscCall(TSGetSNES(ts, &snes));
1312:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1313:   PetscCall(TSGetDM(ts, &dm));
1314:   PetscCall(DMTSGetRHSFunction(dm, func, ctx));
1315:   PetscFunctionReturn(PETSC_SUCCESS);
1316: }

1318: /*@
1319:   TSSetIJacobian - Set the function to compute the matrix dF/dU + a*dF/dU_t where F(t,U,U_t) is the function
1320:   provided with `TSSetIFunction()`.

1322:   Logically Collective

1324:   Input Parameters:
1325: + ts   - the `TS` context obtained from `TSCreate()`
1326: . Amat - (approximate) matrix to store Jacobian entries computed by `f`
1327: . Pmat - matrix used to compute preconditioner (usually the same as `Amat`)
1328: . f    - the Jacobian evaluation routine
1329: - ctx  - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1331:   Level: beginner

1333:   Notes:
1334:   The matrices `Amat` and `Pmat` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1336:   If you know the operator Amat has a null space you can use `MatSetNullSpace()` and `MatSetTransposeNullSpace()` to supply the null
1337:   space to `Amat` and the `KSP` solvers will automatically use that null space as needed during the solution process.

1339:   The matrix dF/dU + a*dF/dU_t you provide turns out to be
1340:   the Jacobian of F(t,U,W+a*U) where F(t,U,U_t) = 0 is the DAE to be solved.
1341:   The time integrator internally approximates U_t by W+a*U where the positive "shift"
1342:   a and vector W depend on the integration method, step size, and past states. For example with
1343:   the backward Euler method a = 1/dt and W = -a*U(previous timestep) so
1344:   W + a*U = a*(U - U(previous timestep)) = (U - U(previous timestep))/dt

1346:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1348:   The TS solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f`
1349:   You should not assume the values are the same in the next call to `f` as you set them in the previous call.

1351:   In case `TSSetRHSJacobian()` is also used in conjunction with a fully-implicit solver,
1352:   multilevel linear solvers, e.g. `PCMG`, will likely not work due to the way `TS` handles rhs matrices.

1354: .seealso: [](ch_ts), `TS`, `TSIJacobianFn`, `TSSetIFunction()`, `TSSetRHSJacobian()`,
1355: `SNESComputeJacobianDefaultColor()`, `SNESComputeJacobianDefault()`, `TSSetRHSFunction()`
1356: @*/
1357: PetscErrorCode TSSetIJacobian(TS ts, Mat Amat, Mat Pmat, TSIJacobianFn *f, PetscCtx ctx)
1358: {
1359:   SNES snes;
1360:   DM   dm;

1362:   PetscFunctionBegin;
1366:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1367:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1369:   PetscCall(TSGetDM(ts, &dm));
1370:   PetscCall(DMTSSetIJacobian(dm, f, ctx));

1372:   PetscCall(TSGetSNES(ts, &snes));
1373:   PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1374:   PetscFunctionReturn(PETSC_SUCCESS);
1375: }

1377: /*@
1378:   TSRHSJacobianSetReuse - restore the RHS Jacobian before calling the user-provided `TSRHSJacobianFn` function again

1380:   Logically Collective

1382:   Input Parameters:
1383: + ts    - `TS` context obtained from `TSCreate()`
1384: - reuse - `PETSC_TRUE` if the RHS Jacobian

1386:   Level: intermediate

1388:   Notes:
1389:   Without this flag, `TS` will change the sign and shift the RHS Jacobian for a
1390:   finite-time-step implicit solve, in which case the user function will need to recompute the
1391:   entire Jacobian.  The `reuse `flag must be set if the evaluation function assumes that the
1392:   matrix entries have not been changed by the `TS`.

1394: .seealso: [](ch_ts), `TS`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
1395: @*/
1396: PetscErrorCode TSRHSJacobianSetReuse(TS ts, PetscBool reuse)
1397: {
1398:   PetscFunctionBegin;
1399:   ts->rhsjacobian.reuse = reuse;
1400:   PetscFunctionReturn(PETSC_SUCCESS);
1401: }

1403: /*@
1404:   TSSetI2Function - Set the function to compute F(t,U,U_t,U_tt) where F = 0 is the DAE to be solved.

1406:   Logically Collective

1408:   Input Parameters:
1409: + ts  - the `TS` context obtained from `TSCreate()`
1410: . F   - vector to hold the residual (or `NULL` to have it created internally)
1411: . fun - the function evaluation routine
1412: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1414:   Level: beginner

1416: .seealso: [](ch_ts), `TS`, `TSI2FunctionFn`, `TSSetI2Jacobian()`, `TSSetIFunction()`,
1417: `TSCreate()`, `TSSetRHSFunction()`
1418: @*/
1419: PetscErrorCode TSSetI2Function(TS ts, Vec F, TSI2FunctionFn *fun, PetscCtx ctx)
1420: {
1421:   DM dm;

1423:   PetscFunctionBegin;
1426:   PetscCall(TSSetIFunction(ts, F, NULL, NULL));
1427:   PetscCall(TSGetDM(ts, &dm));
1428:   PetscCall(DMTSSetI2Function(dm, fun, ctx));
1429:   PetscFunctionReturn(PETSC_SUCCESS);
1430: }

1432: /*@
1433:   TSGetI2Function - Returns the vector where the implicit residual is stored and the function/context to compute it.

1435:   Not Collective

1437:   Input Parameter:
1438: . ts - the `TS` context

1440:   Output Parameters:
1441: + r   - vector to hold residual (or `NULL`)
1442: . fun - the function to compute residual (or `NULL`)
1443: - ctx - the function context (or `NULL`)

1445:   Level: advanced

1447: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`, `TSCreate()`
1448: @*/
1449: PetscErrorCode TSGetI2Function(TS ts, Vec *r, TSI2FunctionFn **fun, PetscCtxRt ctx)
1450: {
1451:   SNES snes;
1452:   DM   dm;

1454:   PetscFunctionBegin;
1456:   PetscCall(TSGetSNES(ts, &snes));
1457:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1458:   PetscCall(TSGetDM(ts, &dm));
1459:   PetscCall(DMTSGetI2Function(dm, fun, ctx));
1460:   PetscFunctionReturn(PETSC_SUCCESS);
1461: }

1463: /*@
1464:   TSSetI2Jacobian - Set the function to compute the matrix dF/dU + v*dF/dU_t  + a*dF/dU_tt
1465:   where F(t,U,U_t,U_tt) is the function you provided with `TSSetI2Function()`.

1467:   Logically Collective

1469:   Input Parameters:
1470: + ts  - the `TS` context obtained from `TSCreate()`
1471: . J   - matrix to hold the Jacobian values
1472: . P   - matrix for constructing the preconditioner (may be same as `J`)
1473: . jac - the Jacobian evaluation routine, see `TSI2JacobianFn` for the calling sequence
1474: - ctx - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1476:   Level: beginner

1478:   Notes:
1479:   The matrices `J` and `P` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1481:   The matrix dF/dU + v*dF/dU_t + a*dF/dU_tt you provide turns out to be
1482:   the Jacobian of G(U) = F(t,U,W+v*U,W'+a*U) where F(t,U,U_t,U_tt) = 0 is the DAE to be solved.
1483:   The time integrator internally approximates U_t by W+v*U and U_tt by W'+a*U  where the positive "shift"
1484:   parameters 'v' and 'a' and vectors W, W' depend on the integration method, step size, and past states.

1486: .seealso: [](ch_ts), `TS`, `TSI2JacobianFn`, `TSSetI2Function()`, `TSGetI2Jacobian()`
1487: @*/
1488: PetscErrorCode TSSetI2Jacobian(TS ts, Mat J, Mat P, TSI2JacobianFn *jac, PetscCtx ctx)
1489: {
1490:   DM dm;

1492:   PetscFunctionBegin;
1496:   PetscCall(TSSetIJacobian(ts, J, P, NULL, NULL));
1497:   PetscCall(TSGetDM(ts, &dm));
1498:   PetscCall(DMTSSetI2Jacobian(dm, jac, ctx));
1499:   PetscFunctionReturn(PETSC_SUCCESS);
1500: }

1502: /*@
1503:   TSGetI2Jacobian - Returns the implicit Jacobian at the present timestep.

1505:   Not Collective, but parallel objects are returned if `TS` is parallel

1507:   Input Parameter:
1508: . ts - The `TS` context obtained from `TSCreate()`

1510:   Output Parameters:
1511: + J   - The (approximate) Jacobian of F(t,U,U_t,U_tt)
1512: . P   - The matrix from which the preconditioner is constructed, often the same as `J`
1513: . jac - The function to compute the Jacobian matrices
1514: - ctx - User-defined context for Jacobian evaluation routine

1516:   Level: advanced

1518:   Note:
1519:   You can pass in `NULL` for any return argument you do not need.

1521: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`, `TSSetI2Jacobian()`, `TSGetI2Function()`, `TSCreate()`
1522: @*/
1523: PetscErrorCode TSGetI2Jacobian(TS ts, Mat *J, Mat *P, TSI2JacobianFn **jac, PetscCtxRt ctx)
1524: {
1525:   SNES snes;
1526:   DM   dm;

1528:   PetscFunctionBegin;
1529:   PetscCall(TSGetSNES(ts, &snes));
1530:   PetscCall(SNESSetUpMatrices(snes));
1531:   PetscCall(SNESGetJacobian(snes, J, P, NULL, NULL));
1532:   PetscCall(TSGetDM(ts, &dm));
1533:   PetscCall(DMTSGetI2Jacobian(dm, jac, ctx));
1534:   PetscFunctionReturn(PETSC_SUCCESS);
1535: }

1537: /*@
1538:   TSComputeI2Function - Evaluates the DAE residual written in implicit form F(t,U,U_t,U_tt) = 0

1540:   Collective

1542:   Input Parameters:
1543: + ts - the `TS` context
1544: . t  - current time
1545: . U  - state vector
1546: . V  - time derivative of state vector (U_t)
1547: - A  - second time derivative of state vector (U_tt)

1549:   Output Parameter:
1550: . F - the residual vector

1552:   Level: developer

1554:   Note:
1555:   Most users should not need to explicitly call this routine, as it
1556:   is used internally within the nonlinear solvers.

1558: .seealso: [](ch_ts), `TS`, `TSSetI2Function()`, `TSGetI2Function()`
1559: @*/
1560: PetscErrorCode TSComputeI2Function(TS ts, PetscReal t, Vec U, Vec V, Vec A, Vec F)
1561: {
1562:   DM               dm;
1563:   TSI2FunctionFn  *I2Function;
1564:   void            *ctx;
1565:   TSRHSFunctionFn *rhsfunction;

1567:   PetscFunctionBegin;

1574:   PetscCall(TSGetDM(ts, &dm));
1575:   PetscCall(DMTSGetI2Function(dm, &I2Function, &ctx));
1576:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));

1578:   if (!I2Function) {
1579:     PetscCall(TSComputeIFunction(ts, t, U, A, F, PETSC_FALSE));
1580:     PetscFunctionReturn(PETSC_SUCCESS);
1581:   }

1583:   PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, V, F));

1585:   PetscCallBack("TS callback implicit function", I2Function(ts, t, U, V, A, F, ctx));

1587:   if (rhsfunction) {
1588:     Vec Frhs;

1590:     PetscCall(DMGetGlobalVector(dm, &Frhs));
1591:     PetscCall(TSComputeRHSFunction(ts, t, U, Frhs));
1592:     PetscCall(VecAXPY(F, -1, Frhs));
1593:     PetscCall(DMRestoreGlobalVector(dm, &Frhs));
1594:   }

1596:   PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, V, F));
1597:   PetscFunctionReturn(PETSC_SUCCESS);
1598: }

1600: /*@
1601:   TSComputeI2Jacobian - Evaluates the Jacobian of the DAE

1603:   Collective

1605:   Input Parameters:
1606: + ts     - the `TS` context
1607: . t      - current timestep
1608: . U      - state vector
1609: . V      - time derivative of state vector
1610: . A      - second time derivative of state vector
1611: . shiftV - shift to apply, see note below
1612: - shiftA - shift to apply, see note below

1614:   Output Parameters:
1615: + J - Jacobian matrix
1616: - P - optional matrix used to construct the preconditioner

1618:   Level: developer

1620:   Notes:
1621:   If $F(t,U,V,A) = 0$ is the DAE, the required Jacobian is

1623: $$
1624:   dF/dU + shiftV*dF/dV + shiftA*dF/dA
1625: $$

1627:   Most users should not need to explicitly call this routine, as it
1628:   is used internally within the ODE integrators.

1630: .seealso: [](ch_ts), `TS`, `TSSetI2Jacobian()`
1631: @*/
1632: PetscErrorCode TSComputeI2Jacobian(TS ts, PetscReal t, Vec U, Vec V, Vec A, PetscReal shiftV, PetscReal shiftA, Mat J, Mat P)
1633: {
1634:   DM               dm;
1635:   TSI2JacobianFn  *I2Jacobian;
1636:   void            *ctx;
1637:   TSRHSJacobianFn *rhsjacobian;

1639:   PetscFunctionBegin;

1647:   PetscCall(TSGetDM(ts, &dm));
1648:   PetscCall(DMTSGetI2Jacobian(dm, &I2Jacobian, &ctx));
1649:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));

1651:   if (!I2Jacobian) {
1652:     PetscCall(TSComputeIJacobian(ts, t, U, A, shiftA, J, P, PETSC_FALSE));
1653:     PetscFunctionReturn(PETSC_SUCCESS);
1654:   }

1656:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, J, P));
1657:   PetscCallBack("TS callback implicit Jacobian", I2Jacobian(ts, t, U, V, A, shiftV, shiftA, J, P, ctx));
1658:   if (rhsjacobian) {
1659:     Mat Jrhs, Prhs;
1660:     PetscCall(TSGetRHSMats_Private(ts, &Jrhs, &Prhs));
1661:     PetscCall(TSComputeRHSJacobian(ts, t, U, Jrhs, Prhs));
1662:     PetscCall(MatAXPY(J, -1, Jrhs, ts->axpy_pattern));
1663:     if (P != J) PetscCall(MatAXPY(P, -1, Prhs, ts->axpy_pattern));
1664:   }

1666:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, J, P));
1667:   PetscFunctionReturn(PETSC_SUCCESS);
1668: }

1670: /*@
1671:   TSSetTransientVariable - sets function to transform from state to transient variables

1673:   Logically Collective

1675:   Input Parameters:
1676: + ts   - time stepping context on which to change the transient variable
1677: . tvar - a function that transforms to transient variables, see `TSTransientVariableFn` for the calling sequence
1678: - ctx  - a context for tvar

1680:   Level: advanced

1682:   Notes:
1683:   This is typically used to transform from primitive to conservative variables so that a time integrator (e.g., `TSBDF`)
1684:   can be conservative.  In this context, primitive variables P are used to model the state (e.g., because they lead to
1685:   well-conditioned formulations even in limiting cases such as low-Mach or zero porosity).  The transient variable is
1686:   C(P), specified by calling this function.  An IFunction thus receives arguments (P, Cdot) and the IJacobian must be
1687:   evaluated via the chain rule, as in
1688: .vb
1689:      dF/dP + shift * dF/dCdot dC/dP.
1690: .ve

1692: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSTransientVariableFn`, `DMTSSetTransientVariable()`, `DMTSGetTransientVariable()`, `TSSetIFunction()`, `TSSetIJacobian()`
1693: @*/
1694: PetscErrorCode TSSetTransientVariable(TS ts, TSTransientVariableFn *tvar, PetscCtx ctx)
1695: {
1696:   DM dm;

1698:   PetscFunctionBegin;
1700:   PetscCall(TSGetDM(ts, &dm));
1701:   PetscCall(DMTSSetTransientVariable(dm, tvar, ctx));
1702:   PetscFunctionReturn(PETSC_SUCCESS);
1703: }

1705: /*@
1706:   TSComputeTransientVariable - transforms state (primitive) variables to transient (conservative) variables

1708:   Logically Collective

1710:   Input Parameters:
1711: + ts - TS on which to compute
1712: - U  - state vector to be transformed to transient variables

1714:   Output Parameter:
1715: . C - transient (conservative) variable

1717:   Level: developer

1719:   Developer Notes:
1720:   If `DMTSSetTransientVariable()` has not been called, then C is not modified in this routine and C = `NULL` is allowed.
1721:   This makes it safe to call without a guard.  One can use `TSHasTransientVariable()` to check if transient variables are
1722:   being used.

1724: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeIFunction()`, `TSComputeIJacobian()`
1725: @*/
1726: PetscErrorCode TSComputeTransientVariable(TS ts, Vec U, Vec C)
1727: {
1728:   DM   dm;
1729:   DMTS dmts;

1731:   PetscFunctionBegin;
1734:   PetscCall(TSGetDM(ts, &dm));
1735:   PetscCall(DMGetDMTS(dm, &dmts));
1736:   if (dmts->ops->transientvar) {
1738:     PetscCall((*dmts->ops->transientvar)(ts, U, C, dmts->transientvarctx));
1739:   }
1740:   PetscFunctionReturn(PETSC_SUCCESS);
1741: }

1743: /*@
1744:   TSHasTransientVariable - determine whether transient variables have been set

1746:   Logically Collective

1748:   Input Parameter:
1749: . ts - `TS` on which to compute

1751:   Output Parameter:
1752: . has - `PETSC_TRUE` if transient variables have been set

1754:   Level: developer

1756: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeTransientVariable()`
1757: @*/
1758: PetscErrorCode TSHasTransientVariable(TS ts, PetscBool *has)
1759: {
1760:   DM   dm;
1761:   DMTS dmts;

1763:   PetscFunctionBegin;
1765:   PetscCall(TSGetDM(ts, &dm));
1766:   PetscCall(DMGetDMTS(dm, &dmts));
1767:   *has = dmts->ops->transientvar ? PETSC_TRUE : PETSC_FALSE;
1768:   PetscFunctionReturn(PETSC_SUCCESS);
1769: }

1771: /*@
1772:   TS2SetSolution - Sets the initial solution and time derivative vectors
1773:   for use by the `TS` routines handling second order equations.

1775:   Logically Collective

1777:   Input Parameters:
1778: + ts - the `TS` context obtained from `TSCreate()`
1779: . u  - the solution vector
1780: - v  - the time derivative vector

1782:   Level: beginner

1784: .seealso: [](ch_ts), `TS`
1785: @*/
1786: PetscErrorCode TS2SetSolution(TS ts, Vec u, Vec v)
1787: {
1788:   PetscFunctionBegin;
1792:   PetscCall(TSSetSolution(ts, u));
1793:   PetscCall(PetscObjectReference((PetscObject)v));
1794:   PetscCall(VecDestroy(&ts->vec_dot));
1795:   ts->vec_dot = v;
1796:   PetscFunctionReturn(PETSC_SUCCESS);
1797: }

1799: /*@
1800:   TS2GetSolution - Returns the solution and time derivative at the present timestep
1801:   for second order equations.

1803:   Not Collective

1805:   Input Parameter:
1806: . ts - the `TS` context obtained from `TSCreate()`

1808:   Output Parameters:
1809: + u - the vector containing the solution
1810: - v - the vector containing the time derivative

1812:   Level: intermediate

1814:   Notes:
1815:   It is valid to call this routine inside the function
1816:   that you are evaluating in order to move to the new timestep. This vector not
1817:   changed until the solution at the next timestep has been calculated.

1819: .seealso: [](ch_ts), `TS`, `TS2SetSolution()`, `TSGetTimeStep()`, `TSGetTime()`
1820: @*/
1821: PetscErrorCode TS2GetSolution(TS ts, Vec *u, Vec *v)
1822: {
1823:   PetscFunctionBegin;
1825:   if (u) PetscAssertPointer(u, 2);
1826:   if (v) PetscAssertPointer(v, 3);
1827:   if (u) *u = ts->vec_sol;
1828:   if (v) *v = ts->vec_dot;
1829:   PetscFunctionReturn(PETSC_SUCCESS);
1830: }

1832: /*@
1833:   TSLoad - Loads a `TS` that has been stored in binary  with `TSView()`.

1835:   Collective

1837:   Input Parameters:
1838: + ts     - the newly loaded `TS`, this needs to have been created with `TSCreate()` or
1839:            some related function before a call to `TSLoad()`.
1840: - viewer - binary file viewer, obtained from `PetscViewerBinaryOpen()`

1842:   Level: intermediate

1844:   Note:
1845:   The type is determined by the data in the file, any type set into the `TS` before this call is ignored.

1847: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerBinaryOpen()`, `TSView()`, `MatLoad()`, `VecLoad()`
1848: @*/
1849: PetscErrorCode TSLoad(TS ts, PetscViewer viewer)
1850: {
1851:   PetscBool isbinary;
1852:   PetscInt  classid;
1853:   char      type[256];
1854:   DMTS      sdm;
1855:   DM        dm;

1857:   PetscFunctionBegin;
1860:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1861:   PetscCheck(isbinary, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid viewer; open viewer with PetscViewerBinaryOpen()");

1863:   PetscCall(PetscViewerBinaryRead(viewer, &classid, 1, NULL, PETSC_INT));
1864:   PetscCheck(classid == TS_FILE_CLASSID, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Not TS next in file");
1865:   PetscCall(PetscViewerBinaryRead(viewer, type, 256, NULL, PETSC_CHAR));
1866:   PetscCall(TSSetType(ts, type));
1867:   PetscTryTypeMethod(ts, load, viewer);
1868:   PetscCall(DMCreate(PetscObjectComm((PetscObject)ts), &dm));
1869:   PetscCall(DMLoad(dm, viewer));
1870:   PetscCall(TSSetDM(ts, dm));
1871:   PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
1872:   PetscCall(VecLoad(ts->vec_sol, viewer));
1873:   PetscCall(DMGetDMTS(ts->dm, &sdm));
1874:   PetscCall(DMTSLoad(sdm, viewer));
1875:   PetscFunctionReturn(PETSC_SUCCESS);
1876: }

1878: #include <petscdraw.h>
1879: #if PetscDefined(HAVE_SAWS)
1880: #include <petscviewersaws.h>
1881: #endif

1883: /*@
1884:   TSViewFromOptions - View a `TS` based on values in the options database

1886:   Collective

1888:   Input Parameters:
1889: + ts   - the `TS` context
1890: . obj  - optional object that provides the prefix for the options database keys, pass `NULL` to use the options prefix of `ts`
1891: - name - command line option string to be passed by user

1893:   Options Database Key:
1894: . -name viewer_specification - See `PetscOptionsCreateViewer()` for the values of `viewer_specification`

1896:   Level: intermediate

1898:   Note:
1899:   This checks the options database, creates the viewer on-the-fly, uses it and then destroys it. Hence it should not be called in heavily used routines,
1900:   rather `PetscOptionsCreateViewer()` should be used to construct the viewer once which can then be utilized in the heavily used routine.

1902: .seealso: [](ch_ts), `TS`, `TSView()`, `PetscObjectViewFromOptions()`, `TSCreate()`, `PetscOptionsCreateViewer()`
1903: @*/
1904: PetscErrorCode TSViewFromOptions(TS ts, PetscObject obj, const char name[])
1905: {
1906:   PetscFunctionBegin;
1908:   PetscCall(PetscObjectViewFromOptions((PetscObject)ts, obj, name));
1909:   PetscFunctionReturn(PETSC_SUCCESS);
1910: }

1912: /*@
1913:   TSView - Displays the `TS` data structure.

1915:   Collective

1917:   Input Parameters:
1918: + ts     - the `TS` context obtained from `TSCreate()`
1919: - viewer - visualization context

1921:   Options Database Key:
1922: . -ts_view viewer_specification - calls `TSView()` at end of `TSStep()`. See `PetscOptionsCreateViewer()` for the format of `viewer_specification`

1924:   Level: beginner

1926:   Notes:
1927:   The available visualization contexts include
1928: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
1929: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
1930:   output where only the first processor opens
1931:   the file.  All other processors send their
1932:   data to the first processor to print.

1934:   The user can open an alternative visualization context with
1935:   `PetscViewerASCIIOpen()` - output to a specified file.

1937:   In the debugger you can do call `TSView`(ts,0) to display the `TS` solver. (The same holds for any PETSc object viewer).

1939:   The "initial time step" displayed is the default time step from `TSCreate()` or that set with `TSSetTimeStep()` or `-ts_time_step`

1941: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerASCIIOpen()`, `PetscOptionsCreateViewer()`, `TSViewFromOptions()`
1942: @*/
1943: PetscErrorCode TSView(TS ts, PetscViewer viewer)
1944: {
1945:   TSType    type;
1946:   PetscBool isascii, isstring, issundials, isbinary, isdraw;
1947:   DMTS      sdm;
1948: #if PetscDefined(HAVE_SAWS)
1949:   PetscBool issaws;
1950: #endif

1952:   PetscFunctionBegin;
1954:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ts), &viewer));
1956:   PetscCheckSameComm(ts, 1, viewer, 2);

1958:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
1959:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
1960:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1961:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
1962: #if PetscDefined(HAVE_SAWS)
1963:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSAWS, &issaws));
1964: #endif
1965:   if (isascii) {
1966:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)ts, viewer));
1967:     if (ts->ops->view) {
1968:       PetscCall(PetscViewerASCIIPushTab(viewer));
1969:       PetscUseTypeMethod(ts, view, viewer);
1970:       PetscCall(PetscViewerASCIIPopTab(viewer));
1971:     }
1972:     PetscCall(PetscViewerASCIIPrintf(viewer, "  initial time step=%g\n", (double)ts->initial_time_step));
1973:     if (ts->max_steps < PETSC_INT_MAX) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum steps=%" PetscInt_FMT "\n", ts->max_steps));
1974:     if (ts->run_steps < PETSC_INT_MAX) PetscCall(PetscViewerASCIIPrintf(viewer, "  run steps=%" PetscInt_FMT "\n", ts->run_steps));
1975:     if (ts->max_time < PETSC_MAX_REAL) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum time=%g\n", (double)ts->max_time));
1976:     if (ts->max_reject != PETSC_UNLIMITED) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum number of step rejections=%" PetscInt_FMT "\n", ts->max_reject));
1977:     if (ts->max_snes_failures != PETSC_UNLIMITED) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum number of SNES failures allowed=%" PetscInt_FMT "\n", ts->max_snes_failures));
1978:     if (ts->ifuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I function evaluations=%" PetscInt_FMT "\n", ts->ifuncs));
1979:     if (ts->ijacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I Jacobian evaluations=%" PetscInt_FMT "\n", ts->ijacs));
1980:     if (ts->rhsfuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS function evaluations=%" PetscInt_FMT "\n", ts->rhsfuncs));
1981:     if (ts->rhsjacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS Jacobian evaluations=%" PetscInt_FMT "\n", ts->rhsjacs));
1982:     if (ts->usessnes) {
1983:       PetscBool lin;
1984:       if (ts->problem_type == TS_NONLINEAR) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of nonlinear solver iterations=%" PetscInt_FMT "\n", ts->snes_its));
1985:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of linear solver iterations=%" PetscInt_FMT "\n", ts->ksp_its));
1986:       PetscCall(PetscObjectTypeCompareAny((PetscObject)ts->snes, &lin, SNESKSPONLY, SNESKSPTRANSPOSEONLY, ""));
1987:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of %slinear solve failures=%" PetscInt_FMT "\n", lin ? "" : "non", ts->num_snes_failures));
1988:     }
1989:     PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of rejected steps=%" PetscInt_FMT "\n", ts->reject));
1990:     if (ts->vrtol) PetscCall(PetscViewerASCIIPrintf(viewer, "  using vector of relative error tolerances, "));
1991:     else PetscCall(PetscViewerASCIIPrintf(viewer, "  using relative error tolerance of %g, ", (double)ts->rtol));
1992:     if (ts->vatol) PetscCall(PetscViewerASCIIPrintf(viewer, "using vector of absolute error tolerances\n"));
1993:     else PetscCall(PetscViewerASCIIPrintf(viewer, "using absolute error tolerance of %g\n", (double)ts->atol));
1994:     PetscCall(PetscViewerASCIIPushTab(viewer));
1995:     PetscCall(TSAdaptView(ts->adapt, viewer));
1996:     PetscCall(PetscViewerASCIIPopTab(viewer));
1997:   } else if (isstring) {
1998:     PetscCall(TSGetType(ts, &type));
1999:     PetscCall(PetscViewerStringSPrintf(viewer, " TSType: %-7.7s", type));
2000:     PetscTryTypeMethod(ts, view, viewer);
2001:   } else if (isbinary) {
2002:     PetscInt    classid = TS_FILE_CLASSID;
2003:     MPI_Comm    comm;
2004:     PetscMPIInt rank;
2005:     char        type[256];

2007:     PetscCall(PetscObjectGetComm((PetscObject)ts, &comm));
2008:     PetscCallMPI(MPI_Comm_rank(comm, &rank));
2009:     if (rank == 0) {
2010:       PetscCall(PetscViewerBinaryWrite(viewer, &classid, 1, PETSC_INT));
2011:       PetscCall(PetscStrncpy(type, ((PetscObject)ts)->type_name, 256));
2012:       PetscCall(PetscViewerBinaryWrite(viewer, type, 256, PETSC_CHAR));
2013:     }
2014:     PetscTryTypeMethod(ts, view, viewer);
2015:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
2016:     PetscCall(DMView(ts->dm, viewer));
2017:     PetscCall(VecView(ts->vec_sol, viewer));
2018:     PetscCall(DMGetDMTS(ts->dm, &sdm));
2019:     PetscCall(DMTSView(sdm, viewer));
2020:   } else if (isdraw) {
2021:     PetscDraw draw;
2022:     char      str[36];
2023:     PetscReal x, y, bottom, h;

2025:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
2026:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
2027:     PetscCall(PetscStrncpy(str, "TS: ", sizeof(str)));
2028:     PetscCall(PetscStrlcat(str, ((PetscObject)ts)->type_name, sizeof(str)));
2029:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_BLACK, PETSC_DRAW_BLACK, str, NULL, &h));
2030:     bottom = y - h;
2031:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
2032:     PetscTryTypeMethod(ts, view, viewer);
2033:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
2034:     if (ts->snes) PetscCall(SNESView(ts->snes, viewer));
2035:     PetscCall(PetscDrawPopCurrentPoint(draw));
2036: #if PetscDefined(HAVE_SAWS)
2037:   } else if (issaws) {
2038:     PetscMPIInt rank;
2039:     const char *name;

2041:     PetscCall(PetscObjectGetName((PetscObject)ts, &name));
2042:     PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
2043:     if (!((PetscObject)ts)->amsmem && rank == 0) {
2044:       char dir[1024];

2046:       PetscCall(PetscObjectViewSAWs((PetscObject)ts, viewer));
2047:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time_step", name));
2048:       PetscCallSAWs(SAWs_Register, (dir, &ts->steps, 1, SAWs_READ, SAWs_INT));
2049:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time", name));
2050:       PetscCallSAWs(SAWs_Register, (dir, &ts->ptime, 1, SAWs_READ, SAWs_DOUBLE));
2051:     }
2052:     PetscTryTypeMethod(ts, view, viewer);
2053: #endif
2054:   }
2055:   if (ts->snes && ts->usessnes) {
2056:     PetscCall(PetscViewerASCIIPushTab(viewer));
2057:     PetscCall(SNESView(ts->snes, viewer));
2058:     PetscCall(PetscViewerASCIIPopTab(viewer));
2059:   }
2060:   PetscCall(DMGetDMTS(ts->dm, &sdm));
2061:   PetscCall(DMTSView(sdm, viewer));

2063:   PetscCall(PetscViewerASCIIPushTab(viewer));
2064:   PetscCall(PetscObjectTypeCompare((PetscObject)ts, TSSUNDIALS, &issundials));
2065:   PetscCall(PetscViewerASCIIPopTab(viewer));
2066:   PetscFunctionReturn(PETSC_SUCCESS);
2067: }

2069: /*@
2070:   TSSetApplicationContext - Sets an optional user-defined context for the timesteppers that may be accessed, for example inside the user provided
2071:   `TS` callbacks with `TSGetApplicationContext()`

2073:   Logically Collective

2075:   Input Parameters:
2076: + ts  - the `TS` context obtained from `TSCreate()`
2077: - ctx - application context

2079:   Level: intermediate

2081:   Fortran Note:
2082:   This only works when `ctx` is a Fortran derived type (it cannot be a `PetscObject`), we recommend writing a Fortran interface definition for this
2083:   function that tells the Fortran compiler the derived data type that is passed in as the `ctx` argument. See `TSGetApplicationContext()` for
2084:   an example.

2086: .seealso: [](ch_ts), `TS`, `TSGetApplicationContext()`
2087: @*/
2088: PetscErrorCode TSSetApplicationContext(TS ts, PetscCtx ctx)
2089: {
2090:   PetscFunctionBegin;
2092:   ts->ctx = ctx;
2093:   PetscFunctionReturn(PETSC_SUCCESS);
2094: }

2096: /*@
2097:   TSGetApplicationContext - Gets the user-defined context for the
2098:   timestepper that was set with `TSSetApplicationContext()`

2100:   Not Collective

2102:   Input Parameter:
2103: . ts - the `TS` context obtained from `TSCreate()`

2105:   Output Parameter:
2106: . ctx - a pointer to the application context

2108:   Level: intermediate

2110:   Fortran Notes:
2111:   This only works when the context is a Fortran derived type or a `PetscObject`. Declare `ctx` with
2112: .vb
2113:   type(tUsertype), pointer :: ctx
2114: .ve

2116: .seealso: [](ch_ts), `TS`, `TSSetApplicationContext()`
2117: @*/
2118: PetscErrorCode TSGetApplicationContext(TS ts, PetscCtxRt ctx)
2119: {
2120:   PetscFunctionBegin;
2122:   *(void **)ctx = ts->ctx;
2123:   PetscFunctionReturn(PETSC_SUCCESS);
2124: }

2126: /*@
2127:   TSGetStepNumber - Gets the number of time steps completed.

2129:   Not Collective

2131:   Input Parameter:
2132: . ts - the `TS` context obtained from `TSCreate()`

2134:   Output Parameter:
2135: . steps - number of steps completed so far

2137:   Level: intermediate

2139: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetTimeStep()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`
2140: @*/
2141: PetscErrorCode TSGetStepNumber(TS ts, PetscInt *steps)
2142: {
2143:   PetscFunctionBegin;
2145:   PetscAssertPointer(steps, 2);
2146:   *steps = ts->steps;
2147:   PetscFunctionReturn(PETSC_SUCCESS);
2148: }

2150: /*@
2151:   TSSetStepNumber - Sets the number of steps completed.

2153:   Logically Collective

2155:   Input Parameters:
2156: + ts    - the `TS` context
2157: - steps - number of steps completed so far

2159:   Level: developer

2161:   Note:
2162:   For most uses of the `TS` solvers the user need not explicitly call
2163:   `TSSetStepNumber()`, as the step counter is appropriately updated in
2164:   `TSSolve()`/`TSStep()`/`TSRollBack()`. Power users may call this routine to
2165:   reinitialize timestepping by setting the step counter to zero (and time
2166:   to the initial time) to solve a similar problem with different initial
2167:   conditions or parameters. Other possible use case is to continue
2168:   timestepping from a previously interrupted run in such a way that `TS`
2169:   monitors will be called with a initial nonzero step counter.

2171: .seealso: [](ch_ts), `TS`, `TSGetStepNumber()`, `TSSetTime()`, `TSSetTimeStep()`, `TSSetSolution()`
2172: @*/
2173: PetscErrorCode TSSetStepNumber(TS ts, PetscInt steps)
2174: {
2175:   PetscFunctionBegin;
2178:   PetscCheck(steps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Step number must be non-negative");
2179:   ts->steps = steps;
2180:   PetscFunctionReturn(PETSC_SUCCESS);
2181: }

2183: /*@
2184:   TSSetTimeStep - Allows one to reset the timestep at any time.

2186:   Logically Collective

2188:   Input Parameters:
2189: + ts        - the `TS` context obtained from `TSCreate()`
2190: - time_step - the size of the timestep

2192:   Options Database Key:
2193: . -ts_time_step dt - provide the initial time step

2195:   Level: intermediate

2197:   Notes:
2198:   This is only a suggestion, the actual initial time step used may differ

2200:   If this is called after `TSSetUp()`, it will not change the initial time step value printed by `TSView()`

2202: .seealso: [](ch_ts), `TS`, `TSPSEUDO`, `TSGetTimeStep()`, `TSSetTime()`
2203: @*/
2204: PetscErrorCode TSSetTimeStep(TS ts, PetscReal time_step)
2205: {
2206:   PetscFunctionBegin;
2209:   ts->time_step = time_step;
2210:   if (ts->setupcalled == PETSC_FALSE) ts->initial_time_step = time_step;
2211:   PetscFunctionReturn(PETSC_SUCCESS);
2212: }

2214: /*@
2215:   TSSetExactFinalTime - Determines whether to adapt the final time step to
2216:   match the exact final time, to interpolate the solution to the exact final time,
2217:   or to just return at the final time `TS` computed (which may be slightly larger
2218:   than the requested final time).

2220:   Logically Collective

2222:   Input Parameters:
2223: + ts     - the time-step context
2224: - eftopt - exact final time option
2225: .vb
2226:   TS_EXACTFINALTIME_STEPOVER    - Don't do anything if final time is exceeded, just use it
2227:   TS_EXACTFINALTIME_INTERPOLATE - Interpolate back to final time if the final time is exceeded
2228:   TS_EXACTFINALTIME_MATCHSTEP   - Adapt final time step to ensure the computed final time exactly equals the requested final time
2229: .ve

2231:   Options Database Key:
2232: . -ts_exact_final_time stepover,interpolate,matchstep - select the final step approach at runtime

2234:   Level: beginner

2236:   Note:
2237:   If you use the option `TS_EXACTFINALTIME_STEPOVER` the solution may be at a very different time
2238:   then the final time you selected.

2240: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSGetExactFinalTime()`
2241: @*/
2242: PetscErrorCode TSSetExactFinalTime(TS ts, TSExactFinalTimeOption eftopt)
2243: {
2244:   PetscFunctionBegin;
2247:   ts->exact_final_time = eftopt;
2248:   PetscFunctionReturn(PETSC_SUCCESS);
2249: }

2251: /*@
2252:   TSGetExactFinalTime - Gets the exact final time option set with `TSSetExactFinalTime()`

2254:   Not Collective

2256:   Input Parameter:
2257: . ts - the `TS` context

2259:   Output Parameter:
2260: . eftopt - exact final time option

2262:   Level: beginner

2264: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSSetExactFinalTime()`
2265: @*/
2266: PetscErrorCode TSGetExactFinalTime(TS ts, TSExactFinalTimeOption *eftopt)
2267: {
2268:   PetscFunctionBegin;
2270:   PetscAssertPointer(eftopt, 2);
2271:   *eftopt = ts->exact_final_time;
2272:   PetscFunctionReturn(PETSC_SUCCESS);
2273: }

2275: /*@
2276:   TSGetTimeStep - Gets the current timestep size.

2278:   Not Collective

2280:   Input Parameter:
2281: . ts - the `TS` context obtained from `TSCreate()`

2283:   Output Parameter:
2284: . dt - the current timestep size

2286:   Level: intermediate

2288: .seealso: [](ch_ts), `TS`, `TSSetTimeStep()`, `TSGetTime()`
2289: @*/
2290: PetscErrorCode TSGetTimeStep(TS ts, PetscReal *dt)
2291: {
2292:   PetscFunctionBegin;
2294:   PetscAssertPointer(dt, 2);
2295:   *dt = ts->time_step;
2296:   PetscFunctionReturn(PETSC_SUCCESS);
2297: }

2299: /*@
2300:   TSGetSolution - Returns the solution at the present timestep. It
2301:   is valid to call this routine inside the function that you are evaluating
2302:   in order to move to the new timestep. This vector not changed until
2303:   the solution at the next timestep has been calculated.

2305:   Not Collective, but v returned is parallel if ts is parallel

2307:   Input Parameter:
2308: . ts - the `TS` context obtained from `TSCreate()`

2310:   Output Parameter:
2311: . v - the vector containing the solution

2313:   Level: intermediate

2315:   Note:
2316:   If you used `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`); this does not return the solution at the requested
2317:   final time. It returns the solution at the next timestep.

2319: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetSolutionComponents()`, `TSSetSolutionFunction()`
2320: @*/
2321: PetscErrorCode TSGetSolution(TS ts, Vec *v)
2322: {
2323:   PetscFunctionBegin;
2325:   PetscAssertPointer(v, 2);
2326:   *v = ts->vec_sol;
2327:   PetscFunctionReturn(PETSC_SUCCESS);
2328: }

2330: /*@
2331:   TSGetSolutionComponents - Returns any solution components at the present
2332:   timestep, if available for the time integration method being used.
2333:   Solution components are quantities that share the same size and
2334:   structure as the solution vector.

2336:   Not Collective, but v returned is parallel if ts is parallel

2338:   Input Parameters:
2339: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2340: . n  - If v is `NULL`, then the number of solution components is
2341:        returned through n, else the n-th solution component is
2342:        returned in v.
2343: - v  - the vector containing the n-th solution component
2344:        (may be `NULL` to use this function to find out
2345:         the number of solutions components).

2347:   Level: advanced

2349: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2350: @*/
2351: PetscErrorCode TSGetSolutionComponents(TS ts, PetscInt *n, Vec *v)
2352: {
2353:   PetscFunctionBegin;
2355:   if (!ts->ops->getsolutioncomponents) *n = 0;
2356:   else PetscUseTypeMethod(ts, getsolutioncomponents, n, v);
2357:   PetscFunctionReturn(PETSC_SUCCESS);
2358: }

2360: /*@
2361:   TSGetAuxSolution - Returns an auxiliary solution at the present
2362:   timestep, if available for the time integration method being used.

2364:   Not Collective, but v returned is parallel if ts is parallel

2366:   Input Parameters:
2367: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2368: - v  - the vector containing the auxiliary solution

2370:   Level: intermediate

2372: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2373: @*/
2374: PetscErrorCode TSGetAuxSolution(TS ts, Vec *v)
2375: {
2376:   PetscFunctionBegin;
2378:   if (ts->ops->getauxsolution) PetscUseTypeMethod(ts, getauxsolution, v);
2379:   else PetscCall(VecZeroEntries(*v));
2380:   PetscFunctionReturn(PETSC_SUCCESS);
2381: }

2383: /*@
2384:   TSGetTimeError - Returns the estimated error vector, if the chosen
2385:   `TSType` has an error estimation functionality and `TSSetTimeError()` was called

2387:   Not Collective, but v returned is parallel if ts is parallel

2389:   Input Parameters:
2390: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2391: . n  - current estimate (n=0) or previous one (n=-1)
2392: - v  - the vector containing the error (same size as the solution).

2394:   Level: intermediate

2396:   Note:
2397:   MUST call after `TSSetUp()`

2399: .seealso: [](ch_ts), `TSGetSolution()`, `TSSetTimeError()`
2400: @*/
2401: PetscErrorCode TSGetTimeError(TS ts, PetscInt n, Vec *v)
2402: {
2403:   PetscFunctionBegin;
2405:   if (ts->ops->gettimeerror) PetscUseTypeMethod(ts, gettimeerror, n, v);
2406:   else PetscCall(VecZeroEntries(*v));
2407:   PetscFunctionReturn(PETSC_SUCCESS);
2408: }

2410: /*@
2411:   TSSetTimeError - Sets the estimated error vector, if the chosen
2412:   `TSType` has an error estimation functionality. This can be used
2413:   to restart such a time integrator with a given error vector.

2415:   Not Collective, but v returned is parallel if ts is parallel

2417:   Input Parameters:
2418: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2419: - v  - the vector containing the error (same size as the solution).

2421:   Level: intermediate

2423: .seealso: [](ch_ts), `TS`, `TSSetSolution()`, `TSGetTimeError()`
2424: @*/
2425: PetscErrorCode TSSetTimeError(TS ts, Vec v)
2426: {
2427:   PetscFunctionBegin;
2429:   PetscCheck(ts->setupcalled, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetUp() first");
2430:   PetscTryTypeMethod(ts, settimeerror, v);
2431:   PetscFunctionReturn(PETSC_SUCCESS);
2432: }

2434: /* ----- Routines to initialize and destroy a timestepper ---- */
2435: /*@
2436:   TSSetProblemType - Sets the type of problem to be solved.

2438:   Not collective

2440:   Input Parameters:
2441: + ts   - The `TS`
2442: - type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2443: .vb
2444:          U_t - A U = 0      (linear)
2445:          U_t - A(t) U = 0   (linear)
2446:          F(t,U,U_t) = 0     (nonlinear)
2447: .ve

2449:   Level: beginner

2451: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2452: @*/
2453: PetscErrorCode TSSetProblemType(TS ts, TSProblemType type)
2454: {
2455:   PetscFunctionBegin;
2457:   ts->problem_type = type;
2458:   if (type == TS_LINEAR) {
2459:     SNES snes;
2460:     PetscCall(TSGetSNES(ts, &snes));
2461:     PetscCall(SNESSetType(snes, SNESKSPONLY));
2462:   }
2463:   PetscFunctionReturn(PETSC_SUCCESS);
2464: }

2466: /*@
2467:   TSGetProblemType - Gets the type of problem to be solved.

2469:   Not collective

2471:   Input Parameter:
2472: . ts - The `TS`

2474:   Output Parameter:
2475: . type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2476: .vb
2477:          M U_t = A U
2478:          M(t) U_t = A(t) U
2479:          F(t,U,U_t)
2480: .ve

2482:   Level: beginner

2484: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2485: @*/
2486: PetscErrorCode TSGetProblemType(TS ts, TSProblemType *type)
2487: {
2488:   PetscFunctionBegin;
2490:   PetscAssertPointer(type, 2);
2491:   *type = ts->problem_type;
2492:   PetscFunctionReturn(PETSC_SUCCESS);
2493: }

2495: /*
2496:     Attempt to check/preset a default value for the exact final time option. This is needed at the beginning of TSSolve() and in TSSetUp()
2497: */
2498: static PetscErrorCode TSSetExactFinalTimeDefault(TS ts)
2499: {
2500:   PetscBool isnone;

2502:   PetscFunctionBegin;
2503:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2504:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2506:   PetscCall(PetscObjectTypeCompare((PetscObject)ts->adapt, TSADAPTNONE, &isnone));
2507:   if (!isnone && ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_MATCHSTEP;
2508:   else if (ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_INTERPOLATE;
2509:   PetscFunctionReturn(PETSC_SUCCESS);
2510: }

2512: /*@
2513:   TSSetUp - Sets up the internal data structures for the later use of a timestepper.

2515:   Collective

2517:   Input Parameter:
2518: . ts - the `TS` context obtained from `TSCreate()`

2520:   Level: advanced

2522:   Note:
2523:   For basic use of the `TS` solvers the user need not explicitly call
2524:   `TSSetUp()`, since these actions will automatically occur during
2525:   the call to `TSStep()` or `TSSolve()`.  However, if one wishes to control this
2526:   phase separately, `TSSetUp()` should be called after `TSCreate()`
2527:   and optional routines of the form TSSetXXX(), but before `TSStep()` and `TSSolve()`.

2529: .seealso: [](ch_ts), `TSCreate()`, `TS`, `TSStep()`, `TSDestroy()`, `TSSolve()`
2530: @*/
2531: PetscErrorCode TSSetUp(TS ts)
2532: {
2533:   DM dm;
2534:   PetscErrorCode (*func)(SNES, Vec, Vec, void *);
2535:   PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *);
2536:   TSIFunctionFn   *ifun;
2537:   TSIJacobianFn   *ijac;
2538:   TSI2JacobianFn  *i2jac;
2539:   TSRHSJacobianFn *rhsjac;

2541:   PetscFunctionBegin;
2543:   if (ts->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);

2545:   if (!((PetscObject)ts)->type_name) {
2546:     PetscCall(TSGetIFunction(ts, NULL, &ifun, NULL));
2547:     PetscCall(TSSetType(ts, ifun ? TSBEULER : TSEULER));
2548:   }

2550:   if (!ts->vec_sol) {
2551:     PetscCheck(ts->dm, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetSolution() first");
2552:     PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
2553:   }

2555:   if (!ts->Jacp && ts->Jacprhs) { /* IJacobianP shares the same matrix with RHSJacobianP if only RHSJacobianP is provided */
2556:     PetscCall(PetscObjectReference((PetscObject)ts->Jacprhs));
2557:     ts->Jacp = ts->Jacprhs;
2558:   }

2560:   if (ts->quadraturets) {
2561:     PetscCall(TSSetUp(ts->quadraturets));
2562:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2563:     PetscCall(VecDuplicate(ts->quadraturets->vec_sol, &ts->vec_costintegrand));
2564:   }

2566:   PetscCall(TSGetRHSJacobian(ts, NULL, NULL, &rhsjac, NULL));
2567:   if (rhsjac == TSComputeRHSJacobianConstant) {
2568:     Mat  Amat, Pmat;
2569:     SNES snes;
2570:     PetscCall(TSGetSNES(ts, &snes));
2571:     PetscCall(SNESGetJacobian(snes, &Amat, &Pmat, NULL, NULL));
2572:     /* Matching matrices implies that an IJacobian is NOT set, because if it had been set, the IJacobian's matrix would
2573:      * have displaced the RHS matrix */
2574:     if (Amat && Amat == ts->Arhs) {
2575:       /* we need to copy the values of the matrix because for the constant Jacobian case the user will never set the numerical values in this new location */
2576:       PetscCall(MatDuplicate(ts->Arhs, MAT_COPY_VALUES, &Amat));
2577:       PetscCall(SNESSetJacobian(snes, Amat, NULL, NULL, NULL));
2578:       PetscCall(MatDestroy(&Amat));
2579:     }
2580:     if (Pmat && Pmat == ts->Brhs) {
2581:       PetscCall(MatDuplicate(ts->Brhs, MAT_COPY_VALUES, &Pmat));
2582:       PetscCall(SNESSetJacobian(snes, NULL, Pmat, NULL, NULL));
2583:       PetscCall(MatDestroy(&Pmat));
2584:     }
2585:   }

2587:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2588:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2590:   PetscTryTypeMethod(ts, setup);

2592:   PetscCall(TSSetExactFinalTimeDefault(ts));

2594:   /* In the case where we've set a DMTSFunction or what have you, we need the default SNESFunction
2595:      to be set right but can't do it elsewhere due to the overreliance on ctx=ts.
2596:    */
2597:   PetscCall(TSGetDM(ts, &dm));
2598:   PetscCall(DMSNESGetFunction(dm, &func, NULL));
2599:   if (!func) PetscCall(DMSNESSetFunction(dm, SNESTSFormFunction, ts));

2601:   /* If the SNES doesn't have a jacobian set and the TS has an ijacobian or rhsjacobian set, set the SNES to use it.
2602:      Otherwise, the SNES will use coloring internally to form the Jacobian.
2603:    */
2604:   PetscCall(DMSNESGetJacobian(dm, &jac, NULL));
2605:   PetscCall(DMTSGetIJacobian(dm, &ijac, NULL));
2606:   PetscCall(DMTSGetI2Jacobian(dm, &i2jac, NULL));
2607:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjac, NULL));
2608:   if (!jac && (ijac || i2jac || rhsjac)) PetscCall(DMSNESSetJacobian(dm, SNESTSFormJacobian, ts));

2610:   /* if time integration scheme has a starting method, call it */
2611:   PetscTryTypeMethod(ts, startingmethod);

2613:   ts->setupcalled = PETSC_TRUE;
2614:   PetscFunctionReturn(PETSC_SUCCESS);
2615: }

2617: /*@
2618:   TSReset - Resets a `TS` context to the state it was in before `TSSetUp()` was called and removes any allocated `Vec` and `Mat` from its data structures

2620:   Collective

2622:   Input Parameter:
2623: . ts - the `TS` context obtained from `TSCreate()`

2625:   Level: developer

2627:   Notes:
2628:   Any options set on the `TS` object, including those set with `TSSetFromOptions()` remain.

2630:   See also `TSSetResize()` to change the size of the system being integrated (for example by adaptive mesh refinement) during the time integration.

2632: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSetResize()`
2633: @*/
2634: PetscErrorCode TSReset(TS ts)
2635: {
2636:   TS_RHSSplitLink ilink = ts->tsrhssplit, next;

2638:   PetscFunctionBegin;

2641:   PetscTryTypeMethod(ts, reset);
2642:   if (ts->snes) PetscCall(SNESReset(ts->snes));
2643:   if (ts->adapt) PetscCall(TSAdaptReset(ts->adapt));

2645:   PetscCall(MatDestroy(&ts->Arhs));
2646:   PetscCall(MatDestroy(&ts->Brhs));
2647:   PetscCall(VecDestroy(&ts->Frhs));
2648:   PetscCall(VecDestroy(&ts->vec_sol));
2649:   PetscCall(VecDestroy(&ts->vec_sol0));
2650:   PetscCall(VecDestroy(&ts->vec_dot));
2651:   PetscCall(VecDestroy(&ts->vatol));
2652:   PetscCall(VecDestroy(&ts->vrtol));
2653:   PetscCall(VecDestroyVecs(ts->nwork, &ts->work));

2655:   PetscCall(MatDestroy(&ts->Jacprhs));
2656:   PetscCall(MatDestroy(&ts->Jacp));
2657:   if (ts->forward_solve) PetscCall(TSForwardReset(ts));
2658:   if (ts->quadraturets) {
2659:     PetscCall(TSReset(ts->quadraturets));
2660:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2661:   }
2662:   while (ilink) {
2663:     next = ilink->next;
2664:     PetscCall(TSDestroy(&ilink->ts));
2665:     PetscCall(PetscFree(ilink->splitname));
2666:     PetscCall(ISDestroy(&ilink->is));
2667:     PetscCall(PetscFree(ilink));
2668:     ilink = next;
2669:   }
2670:   ts->tsrhssplit     = NULL;
2671:   ts->num_rhs_splits = 0;
2672:   if (ts->eval_times) {
2673:     PetscCall(PetscFree(ts->eval_times->time_points));
2674:     PetscCall(PetscFree(ts->eval_times->sol_times));
2675:     PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
2676:     PetscCall(PetscFree(ts->eval_times));
2677:   }
2678:   ts->rhsjacobian.time  = PETSC_MIN_REAL;
2679:   ts->rhsjacobian.scale = 1.0;
2680:   ts->ijacobian.shift   = 1.0;
2681:   ts->setupcalled       = PETSC_FALSE;
2682:   PetscFunctionReturn(PETSC_SUCCESS);
2683: }

2685: static PetscErrorCode TSResizeReset(TS);

2687: /*@
2688:   TSDestroy - Destroys the timestepper context that was created
2689:   with `TSCreate()`.

2691:   Collective

2693:   Input Parameter:
2694: . ts - the `TS` context obtained from `TSCreate()`

2696:   Level: beginner

2698: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSSolve()`
2699: @*/
2700: PetscErrorCode TSDestroy(TS *ts)
2701: {
2702:   PetscFunctionBegin;
2703:   if (!*ts) PetscFunctionReturn(PETSC_SUCCESS);
2705:   if (--((PetscObject)*ts)->refct > 0) {
2706:     *ts = NULL;
2707:     PetscFunctionReturn(PETSC_SUCCESS);
2708:   }

2710:   PetscCall(TSReset(*ts));
2711:   PetscCall(TSAdjointReset(*ts));
2712:   if ((*ts)->forward_solve) PetscCall(TSForwardReset(*ts));
2713:   PetscCall(TSResizeReset(*ts));

2715:   /* if memory was published with SAWs then destroy it */
2716:   PetscCall(PetscObjectSAWsViewOff((PetscObject)*ts));
2717:   PetscTryTypeMethod(*ts, destroy);

2719:   PetscCall(TSTrajectoryDestroy(&(*ts)->trajectory));

2721:   PetscCall(TSAdaptDestroy(&(*ts)->adapt));
2722:   PetscCall(TSEventDestroy(&(*ts)->event));

2724:   PetscCall(SNESDestroy(&(*ts)->snes));
2725:   PetscCall(SNESDestroy(&(*ts)->snesrhssplit));
2726:   PetscCall(DMDestroy(&(*ts)->dm));
2727:   PetscCall(TSMonitorCancel(*ts));
2728:   PetscCall(TSAdjointMonitorCancel(*ts));

2730:   PetscCall(TSDestroy(&(*ts)->quadraturets));
2731:   PetscCall(PetscHeaderDestroy(ts));
2732:   PetscFunctionReturn(PETSC_SUCCESS);
2733: }

2735: /*@
2736:   TSSetSNES - Set the `SNES` (nonlinear solver) to be used by the `TS` timestepping context

2738:   Collective

2740:   Input Parameters:
2741: + ts   - the `TS` context obtained from `TSCreate()`
2742: - snes - the nonlinear solver context

2744:   Level: developer

2746:   Note:
2747:   Most users should obtain the `SNES` by calling `TSGetSNES()` rather than setting it with this function.

2749: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetKSP()`, `TSIsImplicit()`, `TSGetSNES()`
2750:  @*/
2751: PetscErrorCode TSSetSNES(TS ts, SNES snes)
2752: {
2753:   PetscErrorCode (*func)(SNES, Vec, Mat, Mat, void *);

2755:   PetscFunctionBegin;
2758:   PetscCall(PetscObjectReference((PetscObject)snes));
2759:   PetscCall(SNESDestroy(&ts->snes));
2760:   ts->snes = snes;
2761:   PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2762:   PetscCall(SNESGetJacobian(ts->snes, NULL, NULL, &func, NULL));
2763:   if (func == SNESTSFormJacobian) PetscCall(SNESSetJacobian(ts->snes, NULL, NULL, SNESTSFormJacobian, ts));
2764:   PetscFunctionReturn(PETSC_SUCCESS);
2765: }

2767: /*@
2768:   TSGetSNES - Returns the `SNES` (nonlinear solver) associated with
2769:   a `TS` (timestepper) context.

2771:   Not Collective, but `snes` is parallel if `ts` is parallel

2773:   Input Parameter:
2774: . ts - the `TS` context obtained from `TSCreate()`

2776:   Output Parameter:
2777: . snes - the nonlinear solver context

2779:   Level: beginner

2781:   Notes:
2782:   The user can then directly manipulate the `SNES` context to set various
2783:   options, etc.  Likewise, the user can then extract and manipulate the
2784:   `KSP`, and `PC` contexts as well.

2786:   For linear problems, use `TSGetKSP()`.

2788:   For integrators that do not use `SNES` (that is, explicit methods),
2789:   the `snes` exists but is not used. Use `TSIsImplicit()` to determine if the
2790:   method is implicit and uses `snes`.

2792:   Developer Note:
2793:   `TS` manages the life-cycle of the `SNES` object for all `TSType` for the life-time of the `TS` object,
2794:   even explicit methods that do not use `SNES`. This is so that `SNES` options are retained between changes to the `TSType` with `TSSetType()`.

2796: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetKSP()`, `TSIsImplicit()`
2797: @*/
2798: PetscErrorCode TSGetSNES(TS ts, SNES *snes)
2799: {
2800:   PetscFunctionBegin;
2802:   PetscAssertPointer(snes, 2);
2803:   if (!ts->snes) {
2804:     PetscCall(SNESCreate(PetscObjectComm((PetscObject)ts), &ts->snes));
2805:     PetscCall(PetscObjectSetOptions((PetscObject)ts->snes, ((PetscObject)ts)->options));
2806:     PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2807:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->snes, (PetscObject)ts, 1));
2808:     if (ts->dm) PetscCall(SNESSetDM(ts->snes, ts->dm));
2809:     if (ts->problem_type == TS_LINEAR) PetscCall(SNESSetType(ts->snes, SNESKSPONLY));
2810:   }
2811:   *snes = ts->snes;
2812:   PetscFunctionReturn(PETSC_SUCCESS);
2813: }

2815: /*@
2816:   TSIsImplicit - Indicates if a `TS` represents an implicit integrator that uses `SNES`

2818:   Not Collective

2820:   Input Parameter:
2821: . ts - the `TS` context obtained from `TSCreate()`

2823:   Output Parameter:
2824: . isimplicit - if the integrator is implicit and uses either `SNES` or `KSP`

2826:   Level: beginner

2828:   Note:
2829:   For integrators that do not use `SNES` (that is, explicit methods), `snes` exists but is not used.

2831: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetKSP()`, `TSGetSNES()`
2832: @*/
2833: PetscErrorCode TSIsImplicit(TS ts, PetscBool *isimplicit)
2834: {
2835:   PetscFunctionBegin;
2837:   PetscAssertPointer(isimplicit, 2);
2838:   *isimplicit = ts->usessnes;
2839:   PetscFunctionReturn(PETSC_SUCCESS);
2840: }

2842: /*@
2843:   TSGetKSP - Returns the `KSP` (linear solver) associated with
2844:   a `TS` (timestepper) context.

2846:   Not Collective, but `ksp` is parallel if `ts` is parallel

2848:   Input Parameter:
2849: . ts - the `TS` context obtained from `TSCreate()`

2851:   Output Parameter:
2852: . ksp - the nonlinear solver context

2854:   Level: beginner

2856:   Notes:
2857:   The user can then directly manipulate the `KSP` context to set various
2858:   options, etc.  Likewise, the user can then extract and manipulate the
2859:   `PC` context as well.

2861:   For nonlinear problems (`TS_NONLINEAR`), use `TSGetSNES()` followed by `SNESGetKSP()`.

2863:   For integrators that do not use `KSP` (that is, explicit methods),
2864:   `TSGetKSP()` returns a `ksp` that is not used. Use `TSIsImplicit()` to determine if
2865:   the `ksp` is actually used.

2867: .seealso: [](ch_ts), `TS`, `SNES`, `KSP`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetSNES()`, `TSIsImplicit()`
2868: @*/
2869: PetscErrorCode TSGetKSP(TS ts, KSP *ksp)
2870: {
2871:   SNES snes;

2873:   PetscFunctionBegin;
2875:   PetscAssertPointer(ksp, 2);
2876:   PetscCheck(((PetscObject)ts)->type_name, PETSC_COMM_SELF, PETSC_ERR_ARG_NULL, "KSP is not created yet. Call TSSetType() first");
2877:   PetscCheck(ts->problem_type == TS_LINEAR, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "For linear problems only; use TSGetSNES() then SNESGetKSP()");
2878:   PetscCall(TSGetSNES(ts, &snes));
2879:   PetscCall(SNESGetKSP(snes, ksp));
2880:   PetscFunctionReturn(PETSC_SUCCESS);
2881: }

2883: /* ----------- Routines to set solver parameters ---------- */

2885: /*@
2886:   TSSetMaxSteps - Sets the maximum number of steps to use.

2888:   Logically Collective

2890:   Input Parameters:
2891: + ts       - the `TS` context obtained from `TSCreate()`
2892: - maxsteps - maximum number of steps to use

2894:   Options Database Key:
2895: . -ts_max_steps maxsteps - Sets maxsteps

2897:   Level: intermediate

2899:   Note:
2900:   Use `PETSC_DETERMINE` to reset the maximum number of steps to the default from when the object's type was set

2902:   The default maximum number of steps is 5,000

2904:   Fortran Note:
2905:   Use `PETSC_DETERMINE_INTEGER`

2907: .seealso: [](ch_ts), `TS`, `TSGetMaxSteps()`, `TSSetMaxTime()`, `TSSetExactFinalTime()`
2908: @*/
2909: PetscErrorCode TSSetMaxSteps(TS ts, PetscInt maxsteps)
2910: {
2911:   PetscFunctionBegin;
2914:   if (maxsteps == PETSC_DETERMINE) {
2915:     ts->max_steps = ts->default_max_steps;
2916:   } else {
2917:     PetscCheck(maxsteps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of steps must be non-negative");
2918:     ts->max_steps = maxsteps;
2919:   }
2920:   PetscFunctionReturn(PETSC_SUCCESS);
2921: }

2923: /*@
2924:   TSGetMaxSteps - Gets the maximum number of steps to use.

2926:   Not Collective

2928:   Input Parameter:
2929: . ts - the `TS` context obtained from `TSCreate()`

2931:   Output Parameter:
2932: . maxsteps - maximum number of steps to use

2934:   Level: advanced

2936: .seealso: [](ch_ts), `TS`, `TSSetMaxSteps()`, `TSGetMaxTime()`, `TSSetMaxTime()`
2937: @*/
2938: PetscErrorCode TSGetMaxSteps(TS ts, PetscInt *maxsteps)
2939: {
2940:   PetscFunctionBegin;
2942:   PetscAssertPointer(maxsteps, 2);
2943:   *maxsteps = ts->max_steps;
2944:   PetscFunctionReturn(PETSC_SUCCESS);
2945: }

2947: /*@
2948:   TSSetRunSteps - Sets the maximum number of steps to take in each call to `TSSolve()`.

2950:   If the step count when `TSSolve()` is `start_step`, this will stop the simulation once `current_step - start_step >= run_steps`.
2951:   Comparatively, `TSSetMaxSteps()` will stop if `current_step >= max_steps`.
2952:   The simulation will stop when either condition is reached.

2954:   Logically Collective

2956:   Input Parameters:
2957: + ts       - the `TS` context obtained from `TSCreate()`
2958: - runsteps - maximum number of steps to take in each call to `TSSolve()`;

2960:   Options Database Key:
2961: . -ts_run_steps runsteps - Sets runsteps

2963:   Level: intermediate

2965:   Note:
2966:   The default is `PETSC_UNLIMITED`

2968: .seealso: [](ch_ts), `TS`, `TSGetRunSteps()`, `TSSetMaxTime()`, `TSSetExactFinalTime()`, `TSSetMaxSteps()`
2969: @*/
2970: PetscErrorCode TSSetRunSteps(TS ts, PetscInt runsteps)
2971: {
2972:   PetscFunctionBegin;
2975:   if (runsteps == PETSC_DETERMINE) {
2976:     ts->run_steps = PETSC_UNLIMITED;
2977:   } else {
2978:     PetscCheck(runsteps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Max number of steps to take in each call to TSSolve must be non-negative");
2979:     ts->run_steps = runsteps;
2980:   }
2981:   PetscFunctionReturn(PETSC_SUCCESS);
2982: }

2984: /*@
2985:   TSGetRunSteps - Gets the maximum number of steps to take in each call to `TSSolve()`.

2987:   Not Collective

2989:   Input Parameter:
2990: . ts - the `TS` context obtained from `TSCreate()`

2992:   Output Parameter:
2993: . runsteps - maximum number of steps to take in each call to `TSSolve`.

2995:   Level: advanced

2997: .seealso: [](ch_ts), `TS`, `TSSetRunSteps()`, `TSGetMaxTime()`, `TSSetMaxTime()`, `TSGetMaxSteps()`
2998: @*/
2999: PetscErrorCode TSGetRunSteps(TS ts, PetscInt *runsteps)
3000: {
3001:   PetscFunctionBegin;
3003:   PetscAssertPointer(runsteps, 2);
3004:   *runsteps = ts->run_steps;
3005:   PetscFunctionReturn(PETSC_SUCCESS);
3006: }

3008: /*@
3009:   TSSetMaxTime - Sets the maximum (or final) time for timestepping.

3011:   Logically Collective

3013:   Input Parameters:
3014: + ts      - the `TS` context obtained from `TSCreate()`
3015: - maxtime - final time to step to

3017:   Options Database Key:
3018: . -ts_max_time maxtime - Sets maxtime

3020:   Level: intermediate

3022:   Notes:
3023:   Use `PETSC_DETERMINE` to reset the maximum time to the default from when the object's type was set

3025:   The default maximum time is 5.0

3027:   Fortran Note:
3028:   Use `PETSC_DETERMINE_REAL`

3030: .seealso: [](ch_ts), `TS`, `TSGetMaxTime()`, `TSSetMaxSteps()`, `TSSetExactFinalTime()`
3031: @*/
3032: PetscErrorCode TSSetMaxTime(TS ts, PetscReal maxtime)
3033: {
3034:   PetscFunctionBegin;
3037:   if (maxtime == PETSC_DETERMINE) {
3038:     ts->max_time = ts->default_max_time;
3039:   } else {
3040:     ts->max_time = maxtime;
3041:   }
3042:   PetscFunctionReturn(PETSC_SUCCESS);
3043: }

3045: /*@
3046:   TSGetMaxTime - Gets the maximum (or final) time for timestepping.

3048:   Not Collective

3050:   Input Parameter:
3051: . ts - the `TS` context obtained from `TSCreate()`

3053:   Output Parameter:
3054: . maxtime - final time to step to

3056:   Level: advanced

3058: .seealso: [](ch_ts), `TS`, `TSSetMaxTime()`, `TSGetMaxSteps()`, `TSSetMaxSteps()`
3059: @*/
3060: PetscErrorCode TSGetMaxTime(TS ts, PetscReal *maxtime)
3061: {
3062:   PetscFunctionBegin;
3064:   PetscAssertPointer(maxtime, 2);
3065:   *maxtime = ts->max_time;
3066:   PetscFunctionReturn(PETSC_SUCCESS);
3067: }

3069: // PetscClangLinter pragma disable: -fdoc-*
3070: /*@
3071:   TSSetInitialTimeStep - Deprecated, use `TSSetTime()` and `TSSetTimeStep()`.

3073:   Level: deprecated

3075: @*/
3076: PetscErrorCode TSSetInitialTimeStep(TS ts, PetscReal initial_time, PetscReal time_step)
3077: {
3078:   PetscFunctionBegin;
3080:   PetscCall(TSSetTime(ts, initial_time));
3081:   PetscCall(TSSetTimeStep(ts, time_step));
3082:   PetscFunctionReturn(PETSC_SUCCESS);
3083: }

3085: // PetscClangLinter pragma disable: -fdoc-*
3086: /*@
3087:   TSGetDuration - Deprecated, use `TSGetMaxSteps()` and `TSGetMaxTime()`.

3089:   Level: deprecated

3091: @*/
3092: PetscErrorCode TSGetDuration(TS ts, PetscInt *maxsteps, PetscReal *maxtime)
3093: {
3094:   PetscFunctionBegin;
3096:   if (maxsteps) {
3097:     PetscAssertPointer(maxsteps, 2);
3098:     *maxsteps = ts->max_steps;
3099:   }
3100:   if (maxtime) {
3101:     PetscAssertPointer(maxtime, 3);
3102:     *maxtime = ts->max_time;
3103:   }
3104:   PetscFunctionReturn(PETSC_SUCCESS);
3105: }

3107: // PetscClangLinter pragma disable: -fdoc-*
3108: /*@
3109:   TSSetDuration - Deprecated, use `TSSetMaxSteps()` and `TSSetMaxTime()`.

3111:   Level: deprecated

3113: @*/
3114: PetscErrorCode TSSetDuration(TS ts, PetscInt maxsteps, PetscReal maxtime)
3115: {
3116:   PetscFunctionBegin;
3117:   if (maxsteps != PETSC_CURRENT) PetscCall(TSSetMaxSteps(ts, maxsteps));
3118:   if (maxtime != (PetscReal)PETSC_CURRENT) PetscCall(TSSetMaxTime(ts, maxtime));
3119:   PetscFunctionReturn(PETSC_SUCCESS);
3120: }

3122: // PetscClangLinter pragma disable: -fdoc-*
3123: /*@
3124:   TSGetTimeStepNumber - Deprecated, use `TSGetStepNumber()`.

3126:   Level: deprecated

3128: @*/
3129: PetscErrorCode TSGetTimeStepNumber(TS ts, PetscInt *steps)
3130: {
3131:   return TSGetStepNumber(ts, steps);
3132: }

3134: // PetscClangLinter pragma disable: -fdoc-*
3135: /*@
3136:   TSGetTotalSteps - Deprecated, use `TSGetStepNumber()`.

3138:   Level: deprecated

3140: @*/
3141: PetscErrorCode TSGetTotalSteps(TS ts, PetscInt *steps)
3142: {
3143:   return TSGetStepNumber(ts, steps);
3144: }

3146: /*@
3147:   TSSetSolution - Sets the initial solution vector
3148:   for use by the `TS` routines.

3150:   Logically Collective

3152:   Input Parameters:
3153: + ts - the `TS` context obtained from `TSCreate()`
3154: - u  - the solution vector

3156:   Level: beginner

3158: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSGetSolution()`, `TSCreate()`
3159: @*/
3160: PetscErrorCode TSSetSolution(TS ts, Vec u)
3161: {
3162:   DM dm;

3164:   PetscFunctionBegin;
3167:   PetscCall(PetscObjectReference((PetscObject)u));
3168:   PetscCall(VecDestroy(&ts->vec_sol));
3169:   ts->vec_sol = u;

3171:   PetscCall(TSGetDM(ts, &dm));
3172:   PetscCall(DMShellSetGlobalVector(dm, u));
3173:   PetscFunctionReturn(PETSC_SUCCESS);
3174: }

3176: /*@
3177:   TSSetPreStep - Sets the general-purpose function
3178:   called once at the beginning of each time step.

3180:   Logically Collective

3182:   Input Parameters:
3183: + ts   - The `TS` context obtained from `TSCreate()`
3184: - func - The function

3186:   Calling sequence of `func`:
3187: . ts - the `TS` context

3189:   Level: intermediate

3191: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`, `TSStep()`, `TSRestartStep()`
3192: @*/
3193: PetscErrorCode TSSetPreStep(TS ts, PetscErrorCode (*func)(TS ts))
3194: {
3195:   PetscFunctionBegin;
3197:   ts->prestep = func;
3198:   PetscFunctionReturn(PETSC_SUCCESS);
3199: }

3201: /*@
3202:   TSPreStep - Runs the user-defined pre-step function provided with `TSSetPreStep()`

3204:   Collective

3206:   Input Parameter:
3207: . ts - The `TS` context obtained from `TSCreate()`

3209:   Level: developer

3211:   Note:
3212:   `TSPreStep()` is typically used within time stepping implementations,
3213:   so most users would not generally call this routine themselves.

3215: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSPreStage()`, `TSPostStage()`, `TSPostStep()`
3216: @*/
3217: PetscErrorCode TSPreStep(TS ts)
3218: {
3219:   PetscFunctionBegin;
3221:   if (ts->prestep) {
3222:     Vec              U;
3223:     PetscObjectId    idprev;
3224:     PetscBool        sameObject;
3225:     PetscObjectState sprev, spost;

3227:     PetscCall(TSGetSolution(ts, &U));
3228:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3229:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3230:     PetscCallBack("TS callback preset", (*ts->prestep)(ts));
3231:     PetscCall(TSGetSolution(ts, &U));
3232:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3233:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3234:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3235:   }
3236:   PetscFunctionReturn(PETSC_SUCCESS);
3237: }

3239: /*@
3240:   TSSetPreStage - Sets the general-purpose function
3241:   called once at the beginning of each stage.

3243:   Logically Collective

3245:   Input Parameters:
3246: + ts   - The `TS` context obtained from `TSCreate()`
3247: - func - The function

3249:   Calling sequence of `func`:
3250: + ts        - the `TS` context
3251: - stagetime - the stage time

3253:   Level: intermediate

3255:   Note:
3256:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3257:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3258:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3260: .seealso: [](ch_ts), `TS`, `TSSetPostStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3261: @*/
3262: PetscErrorCode TSSetPreStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime))
3263: {
3264:   PetscFunctionBegin;
3266:   ts->prestage = func;
3267:   PetscFunctionReturn(PETSC_SUCCESS);
3268: }

3270: /*@
3271:   TSSetPostStage - Sets the general-purpose function
3272:   called once at the end of each stage.

3274:   Logically Collective

3276:   Input Parameters:
3277: + ts   - The `TS` context obtained from `TSCreate()`
3278: - func - The function

3280:   Calling sequence of `func`:
3281: + ts         - the `TS` context
3282: . stagetime  - the stage time
3283: . stageindex - the stage index
3284: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3286:   Level: intermediate

3288:   Note:
3289:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3290:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3291:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3293: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3294: @*/
3295: PetscErrorCode TSSetPostStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime, PetscInt stageindex, Vec *Y))
3296: {
3297:   PetscFunctionBegin;
3299:   ts->poststage = func;
3300:   PetscFunctionReturn(PETSC_SUCCESS);
3301: }

3303: /*@
3304:   TSSetPostEvaluate - Sets the general-purpose function
3305:   called at the end of each step evaluation.

3307:   Logically Collective

3309:   Input Parameters:
3310: + ts   - The `TS` context obtained from `TSCreate()`
3311: - func - The function

3313:   Calling sequence of `func`:
3314: . ts - the `TS` context

3316:   Level: intermediate

3318:   Note:
3319:   The function set by `TSSetPostEvaluate()` is called after the solution is evaluated, or after the step rollback.
3320:   Inside the `func` callback, the solution vector can be obtained with `TSGetSolution()`, and modified, if need be.
3321:   The time step can be obtained with `TSGetTimeStep()`, and the time at the start of the step - via `TSGetTime()`.
3322:   The potential changes to the solution vector introduced by event handling (`postevent()`) are not relevant for `TSSetPostEvaluate()`,
3323:   but are relevant for `TSSetPostStep()`, according to the function call scheme in `TSSolve()`, as shown below
3324: .vb
3325:   ...
3326:   Step()
3327:   PostEvaluate()
3328:   EventHandling()
3329:   step_rollback ? PostEvaluate() : PostStep()
3330:   ...
3331: .ve
3332:   where EventHandling() may result in one of the following three outcomes
3333: .vb
3334:   (1) | successful step | solution intact
3335:   (2) | successful step | solution modified by `postevent()`
3336:   (3) | step_rollback   | solution rolled back
3337: .ve

3339: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3340: @*/
3341: PetscErrorCode TSSetPostEvaluate(TS ts, PetscErrorCode (*func)(TS ts))
3342: {
3343:   PetscFunctionBegin;
3345:   ts->postevaluate = func;
3346:   PetscFunctionReturn(PETSC_SUCCESS);
3347: }

3349: /*@
3350:   TSPreStage - Runs the user-defined pre-stage function set using `TSSetPreStage()`

3352:   Collective

3354:   Input Parameters:
3355: + ts        - The `TS` context obtained from `TSCreate()`
3356: - stagetime - The absolute time of the current stage

3358:   Level: developer

3360:   Note:
3361:   `TSPreStage()` is typically used within time stepping implementations,
3362:   most users would not generally call this routine themselves.

3364: .seealso: [](ch_ts), `TS`, `TSPostStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3365: @*/
3366: PetscErrorCode TSPreStage(TS ts, PetscReal stagetime)
3367: {
3368:   PetscFunctionBegin;
3370:   if (ts->prestage) PetscCallBack("TS callback prestage", (*ts->prestage)(ts, stagetime));
3371:   PetscFunctionReturn(PETSC_SUCCESS);
3372: }

3374: /*@
3375:   TSPostStage - Runs the user-defined post-stage function set using `TSSetPostStage()`

3377:   Collective

3379:   Input Parameters:
3380: + ts         - The `TS` context obtained from `TSCreate()`
3381: . stagetime  - The absolute time of the current stage
3382: . stageindex - Stage number
3383: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3385:   Level: developer

3387:   Note:
3388:   `TSPostStage()` is typically used within time stepping implementations,
3389:   most users would not generally call this routine themselves.

3391: .seealso: [](ch_ts), `TS`, `TSPreStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3392: @*/
3393: PetscErrorCode TSPostStage(TS ts, PetscReal stagetime, PetscInt stageindex, Vec Y[])
3394: {
3395:   PetscFunctionBegin;
3397:   if (ts->poststage) PetscCallBack("TS callback poststage", (*ts->poststage)(ts, stagetime, stageindex, Y));
3398:   PetscFunctionReturn(PETSC_SUCCESS);
3399: }

3401: /*@
3402:   TSPostEvaluate - Runs the user-defined post-evaluate function set using `TSSetPostEvaluate()`

3404:   Collective

3406:   Input Parameter:
3407: . ts - The `TS` context obtained from `TSCreate()`

3409:   Level: developer

3411:   Note:
3412:   `TSPostEvaluate()` is typically used within time stepping implementations,
3413:   most users would not generally call this routine themselves.

3415: .seealso: [](ch_ts), `TS`, `TSSetPostEvaluate()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3416: @*/
3417: PetscErrorCode TSPostEvaluate(TS ts)
3418: {
3419:   PetscFunctionBegin;
3421:   if (ts->postevaluate) {
3422:     Vec              U;
3423:     PetscObjectState sprev, spost;

3425:     PetscCall(TSGetSolution(ts, &U));
3426:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3427:     PetscCallBack("TS callback postevaluate", (*ts->postevaluate)(ts));
3428:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3429:     if (sprev != spost) PetscCall(TSRestartStep(ts));
3430:   }
3431:   PetscFunctionReturn(PETSC_SUCCESS);
3432: }

3434: /*@
3435:   TSSetPostStep - Sets the general-purpose function
3436:   called once at the end of each successful time step.

3438:   Logically Collective

3440:   Input Parameters:
3441: + ts   - The `TS` context obtained from `TSCreate()`
3442: - func - The function

3444:   Calling sequence of `func`:
3445: . ts - the `TS` context

3447:   Level: intermediate

3449:   Note:
3450:   The function set by `TSSetPostStep()` is called after each successful step. If the event handler locates an event at the
3451:   given step, and `postevent()` modifies the solution vector, the solution vector obtained by `TSGetSolution()` inside `func` will
3452:   contain the changes. To get the solution without these changes, use `TSSetPostEvaluate()` to set the appropriate callback.
3453:   The scheme of the relevant function calls in `TSSolve()` is shown below
3454: .vb
3455:   ...
3456:   Step()
3457:   PostEvaluate()
3458:   EventHandling()
3459:   step_rollback ? PostEvaluate() : PostStep()
3460:   ...
3461: .ve
3462:   where EventHandling() may result in one of the following three outcomes
3463: .vb
3464:   (1) | successful step | solution intact
3465:   (2) | successful step | solution modified by `postevent()`
3466:   (3) | step_rollback   | solution rolled back
3467: .ve

3469: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSRestartStep()`
3470: @*/
3471: PetscErrorCode TSSetPostStep(TS ts, PetscErrorCode (*func)(TS ts))
3472: {
3473:   PetscFunctionBegin;
3475:   ts->poststep = func;
3476:   PetscFunctionReturn(PETSC_SUCCESS);
3477: }

3479: /*@
3480:   TSPostStep - Runs the user-defined post-step function that was set with `TSSetPostStep()`

3482:   Collective

3484:   Input Parameter:
3485: . ts - The `TS` context obtained from `TSCreate()`

3487:   Note:
3488:   `TSPostStep()` is typically used within time stepping implementations,
3489:   so most users would not generally call this routine themselves.

3491:   Level: developer

3493: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSSetPostStep()`
3494: @*/
3495: PetscErrorCode TSPostStep(TS ts)
3496: {
3497:   PetscFunctionBegin;
3499:   if (ts->poststep) {
3500:     Vec              U;
3501:     PetscObjectId    idprev;
3502:     PetscBool        sameObject;
3503:     PetscObjectState sprev, spost;

3505:     PetscCall(TSGetSolution(ts, &U));
3506:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3507:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3508:     PetscCallBack("TS callback poststep", (*ts->poststep)(ts));
3509:     PetscCall(TSGetSolution(ts, &U));
3510:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3511:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3512:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3513:   }
3514:   PetscFunctionReturn(PETSC_SUCCESS);
3515: }

3517: /*@
3518:   TSInterpolate - Interpolate the solution computed during the previous step to an arbitrary location in the interval

3520:   Collective

3522:   Input Parameters:
3523: + ts - time stepping context
3524: - t  - time to interpolate to

3526:   Output Parameter:
3527: . U - state at given time

3529:   Level: intermediate

3531:   Developer Notes:
3532:   `TSInterpolate()` and the storing of previous steps/stages should be generalized to support delay differential equations and continuous adjoints.

3534: .seealso: [](ch_ts), `TS`, `TSSetExactFinalTime()`, `TSSolve()`
3535: @*/
3536: PetscErrorCode TSInterpolate(TS ts, PetscReal t, Vec U)
3537: {
3538:   PetscFunctionBegin;
3541:   PetscCheck(t >= ts->ptime_prev && t <= ts->ptime, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Requested time %g not in last time steps [%g,%g]", (double)t, (double)ts->ptime_prev, (double)ts->ptime);
3542:   PetscUseTypeMethod(ts, interpolate, t, U);
3543:   PetscFunctionReturn(PETSC_SUCCESS);
3544: }

3546: /*@
3547:   TSStep - Steps one time step

3549:   Collective

3551:   Input Parameter:
3552: . ts - the `TS` context obtained from `TSCreate()`

3554:   Level: developer

3556:   Notes:
3557:   The public interface for the ODE/DAE solvers is `TSSolve()`, you should almost for sure be using that routine and not this routine.

3559:   The hook set using `TSSetPreStep()` is called before each attempt to take the step. In general, the time step size may
3560:   be changed due to adaptive error controller or solve failures. Note that steps may contain multiple stages.

3562:   This may over-step the final time provided in `TSSetMaxTime()` depending on the time-step used. `TSSolve()` interpolates to exactly the
3563:   time provided in `TSSetMaxTime()`. One can use `TSInterpolate()` to determine an interpolated solution within the final timestep.

3565: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSInterpolate()`
3566: @*/
3567: PetscErrorCode TSStep(TS ts)
3568: {
3569:   static PetscBool cite = PETSC_FALSE;
3570:   PetscReal        ptime;

3572:   PetscFunctionBegin;
3574:   PetscCall(PetscCitationsRegister("@article{tspaper,\n"
3575:                                    "  title         = {{PETSc/TS}: A Modern Scalable {DAE/ODE} Solver Library},\n"
3576:                                    "  author        = {Abhyankar, Shrirang and Brown, Jed and Constantinescu, Emil and Ghosh, Debojyoti and Smith, Barry F. and Zhang, Hong},\n"
3577:                                    "  journal       = {arXiv e-preprints},\n"
3578:                                    "  eprint        = {1806.01437},\n"
3579:                                    "  archivePrefix = {arXiv},\n"
3580:                                    "  year          = {2018}\n}\n",
3581:                                    &cite));
3582:   PetscCall(TSSetUp(ts));
3583:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));
3584:   if (ts->eval_times)
3585:     ts->eval_times->worktol = 0; /* In each step of TSSolve() 'eval_times->worktol' will be meaningfully defined (later) only once:
3586:                                                    in TSAdaptChoose() or TSEvent_dt_cap(), and then reused till the end of the step */

3588:   PetscCheck(ts->max_time < PETSC_MAX_REAL || ts->run_steps != PETSC_INT_MAX || ts->max_steps != PETSC_INT_MAX, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetMaxTime(), TSSetMaxSteps(), or TSSetRunSteps() or use -ts_max_time <time>, -ts_max_steps <steps>, -ts_run_steps <steps>");
3589:   PetscCheck(ts->exact_final_time != TS_EXACTFINALTIME_UNSPECIFIED, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetExactFinalTime() or use -ts_exact_final_time <stepover,interpolate,matchstep> before calling TSStep()");
3590:   PetscCheck(ts->exact_final_time != TS_EXACTFINALTIME_MATCHSTEP || ts->adapt, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Since TS is not adaptive you cannot use TS_EXACTFINALTIME_MATCHSTEP, suggest TS_EXACTFINALTIME_INTERPOLATE");

3592:   if (!ts->vec_sol0) PetscCall(VecDuplicate(ts->vec_sol, &ts->vec_sol0));
3593:   PetscCall(VecCopy(ts->vec_sol, ts->vec_sol0));
3594:   ts->time_step0 = ts->time_step;

3596:   if (!ts->steps) ts->ptime_prev = ts->ptime;
3597:   ptime = ts->ptime;

3599:   ts->ptime_prev_rollback = ts->ptime_prev;
3600:   ts->reason              = TS_CONVERGED_ITERATING;

3602:   PetscCall(PetscLogEventBegin(TS_Step, ts, 0, 0, 0));
3603:   PetscUseTypeMethod(ts, step);
3604:   PetscCall(PetscLogEventEnd(TS_Step, ts, 0, 0, 0));

3606:   if (ts->reason >= 0) {
3607:     ts->ptime_prev = ptime;
3608:     ts->steps++;
3609:     ts->steprollback = PETSC_FALSE;
3610:     ts->steprestart  = PETSC_FALSE;
3611:     ts->stepresize   = PETSC_FALSE;
3612:   }

3614:   if (ts->reason < 0 && ts->errorifstepfailed) {
3615:     PetscCall(TSMonitorCancel(ts));
3616:     if (ts->usessnes && ts->snes) PetscCall(SNESMonitorCancel(ts->snes));
3617:     PetscCheck(ts->reason != TS_DIVERGED_NONLINEAR_SOLVE, PetscObjectComm((PetscObject)ts), PETSC_ERR_NOT_CONVERGED, "TSStep has failed due to %s, increase -ts_max_snes_failures or use unlimited to attempt recovery", TSConvergedReasons[ts->reason]);
3618:     SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_NOT_CONVERGED, "TSStep has failed due to %s", TSConvergedReasons[ts->reason]);
3619:   }
3620:   PetscFunctionReturn(PETSC_SUCCESS);
3621: }

3623: /*@
3624:   TSEvaluateWLTE - Evaluate the weighted local truncation error norm
3625:   at the end of a time step with a given order of accuracy.

3627:   Collective

3629:   Input Parameters:
3630: + ts        - time stepping context
3631: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

3633:   Input/Output Parameter:
3634: . order - optional, desired order for the error evaluation or `PETSC_DECIDE`;
3635:            on output, the actual order of the error evaluation

3637:   Output Parameter:
3638: . wlte - the weighted local truncation error norm

3640:   Level: advanced

3642:   Note:
3643:   If the timestepper cannot evaluate the error in a particular step
3644:   (eg. in the first step or restart steps after event handling),
3645:   this routine returns wlte=-1.0 .

3647: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`, `TSErrorWeightedNorm()`
3648: @*/
3649: PetscErrorCode TSEvaluateWLTE(TS ts, NormType wnormtype, PetscInt *order, PetscReal *wlte)
3650: {
3651:   PetscFunctionBegin;
3655:   if (order) PetscAssertPointer(order, 3);
3657:   PetscAssertPointer(wlte, 4);
3658:   PetscCheck(wnormtype == NORM_2 || wnormtype == NORM_INFINITY, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No support for norm type %s", NormTypes[wnormtype]);
3659:   PetscUseTypeMethod(ts, evaluatewlte, wnormtype, order, wlte);
3660:   PetscFunctionReturn(PETSC_SUCCESS);
3661: }

3663: /*@
3664:   TSEvaluateStep - Evaluate the solution at the end of a time step with a given order of accuracy.

3666:   Collective

3668:   Input Parameters:
3669: + ts    - time stepping context
3670: . order - desired order of accuracy
3671: - done  - whether the step was evaluated at this order (pass `NULL` to generate an error if not available)

3673:   Output Parameter:
3674: . U - state at the end of the current step

3676:   Level: advanced

3678:   Notes:
3679:   This function cannot be called until all stages have been evaluated.

3681:   It is normally called by adaptive controllers before a step has been accepted and may also be called by the user after `TSStep()` has returned.

3683: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`
3684: @*/
3685: PetscErrorCode TSEvaluateStep(TS ts, PetscInt order, Vec U, PetscBool *done)
3686: {
3687:   PetscFunctionBegin;
3691:   PetscUseTypeMethod(ts, evaluatestep, order, U, done);
3692:   PetscFunctionReturn(PETSC_SUCCESS);
3693: }

3695: /*@
3696:   TSGetComputeInitialCondition - Get the function used to automatically compute an initial condition for the timestepping.

3698:   Not collective

3700:   Input Parameter:
3701: . ts - time stepping context

3703:   Output Parameter:
3704: . initCondition - The function which computes an initial condition

3706:   Calling sequence of `initCondition`:
3707: + ts - The timestepping context
3708: - u  - The input vector in which the initial condition is stored

3710:   Level: advanced

3712: .seealso: [](ch_ts), `TS`, `TSSetComputeInitialCondition()`, `TSComputeInitialCondition()`
3713: @*/
3714: PetscErrorCode TSGetComputeInitialCondition(TS ts, PetscErrorCode (**initCondition)(TS ts, Vec u))
3715: {
3716:   PetscFunctionBegin;
3718:   PetscAssertPointer(initCondition, 2);
3719:   *initCondition = ts->ops->initcondition;
3720:   PetscFunctionReturn(PETSC_SUCCESS);
3721: }

3723: /*@
3724:   TSSetComputeInitialCondition - Set the function used to automatically compute an initial condition for the timestepping.

3726:   Logically collective

3728:   Input Parameters:
3729: + ts            - time stepping context
3730: - initCondition - The function which computes an initial condition

3732:   Calling sequence of `initCondition`:
3733: + ts - The timestepping context
3734: - e  - The input vector in which the initial condition is to be stored

3736:   Level: advanced

3738: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSComputeInitialCondition()`
3739: @*/
3740: PetscErrorCode TSSetComputeInitialCondition(TS ts, PetscErrorCode (*initCondition)(TS ts, Vec e))
3741: {
3742:   PetscFunctionBegin;
3745:   ts->ops->initcondition = initCondition;
3746:   PetscFunctionReturn(PETSC_SUCCESS);
3747: }

3749: /*@
3750:   TSComputeInitialCondition - Compute an initial condition for the timestepping using the function previously set with `TSSetComputeInitialCondition()`

3752:   Collective

3754:   Input Parameters:
3755: + ts - time stepping context
3756: - u  - The `Vec` to store the condition in which will be used in `TSSolve()`

3758:   Level: advanced

3760: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3761: @*/
3762: PetscErrorCode TSComputeInitialCondition(TS ts, Vec u)
3763: {
3764:   PetscFunctionBegin;
3767:   PetscTryTypeMethod(ts, initcondition, u);
3768:   PetscFunctionReturn(PETSC_SUCCESS);
3769: }

3771: /*@
3772:   TSGetComputeExactError - Get the function used to automatically compute the exact error for the timestepping.

3774:   Not collective

3776:   Input Parameter:
3777: . ts - time stepping context

3779:   Output Parameter:
3780: . exactError - The function which computes the solution error

3782:   Calling sequence of `exactError`:
3783: + ts - The timestepping context
3784: . u  - The approximate solution vector
3785: - e  - The vector in which the error is stored

3787:   Level: advanced

3789: .seealso: [](ch_ts), `TS`, `TSComputeExactError()`
3790: @*/
3791: PetscErrorCode TSGetComputeExactError(TS ts, PetscErrorCode (**exactError)(TS ts, Vec u, Vec e))
3792: {
3793:   PetscFunctionBegin;
3795:   PetscAssertPointer(exactError, 2);
3796:   *exactError = ts->ops->exacterror;
3797:   PetscFunctionReturn(PETSC_SUCCESS);
3798: }

3800: /*@
3801:   TSSetComputeExactError - Set the function used to automatically compute the exact error for the timestepping.

3803:   Logically collective

3805:   Input Parameters:
3806: + ts         - time stepping context
3807: - exactError - The function which computes the solution error

3809:   Calling sequence of `exactError`:
3810: + ts - The timestepping context
3811: . u  - The approximate solution vector
3812: - e  - The  vector in which the error is stored

3814:   Level: advanced

3816: .seealso: [](ch_ts), `TS`, `TSGetComputeExactError()`, `TSComputeExactError()`
3817: @*/
3818: PetscErrorCode TSSetComputeExactError(TS ts, PetscErrorCode (*exactError)(TS ts, Vec u, Vec e))
3819: {
3820:   PetscFunctionBegin;
3823:   ts->ops->exacterror = exactError;
3824:   PetscFunctionReturn(PETSC_SUCCESS);
3825: }

3827: /*@
3828:   TSComputeExactError - Compute the solution error for the timestepping using the function previously set with `TSSetComputeExactError()`

3830:   Collective

3832:   Input Parameters:
3833: + ts - time stepping context
3834: . u  - The approximate solution
3835: - e  - The `Vec` used to store the error

3837:   Level: advanced

3839: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3840: @*/
3841: PetscErrorCode TSComputeExactError(TS ts, Vec u, Vec e)
3842: {
3843:   PetscFunctionBegin;
3847:   PetscTryTypeMethod(ts, exacterror, u, e);
3848:   PetscFunctionReturn(PETSC_SUCCESS);
3849: }

3851: /*@
3852:   TSSetResize - Sets the resize callbacks.

3854:   Logically Collective

3856:   Input Parameters:
3857: + ts       - The `TS` context obtained from `TSCreate()`
3858: . rollback - Whether a resize will restart the step
3859: . setup    - The setup function
3860: . transfer - The transfer function
3861: - ctx      - [optional] The user-defined context

3863:   Calling sequence of `setup`:
3864: + ts     - the `TS` context
3865: . step   - the current step
3866: . time   - the current time
3867: . state  - the current vector of state
3868: . resize - (output parameter) `PETSC_TRUE` if need resizing, `PETSC_FALSE` otherwise
3869: - ctx    - user defined context

3871:   Calling sequence of `transfer`:
3872: + ts      - the `TS` context
3873: . nv      - the number of vectors to be transferred
3874: . vecsin  - array of vectors to be transferred
3875: . vecsout - array of transferred vectors
3876: - ctx     - user defined context

3878:   Notes:
3879:   The `setup` function is called inside `TSSolve()` after `TSEventHandler()` or after `TSPostStep()`
3880:   depending on the `rollback` value: if `rollback` is true, then these callbacks behave as error indicators
3881:   and will flag the need to remesh and restart the current step. Otherwise, they will simply flag the solver
3882:   that the size of the discrete problem has changed.
3883:   In both cases, the solver will collect the needed vectors that will be
3884:   transferred from the old to the new sizes using the `transfer` callback. These vectors will include the
3885:   current solution vector, and other vectors needed by the specific solver used.
3886:   For example, `TSBDF` uses previous solutions vectors to solve for the next time step.
3887:   Other application specific objects associated with the solver, i.e. Jacobian matrices and `DM`,
3888:   will be automatically reset if the sizes are changed and they must be specified again by the user
3889:   inside the `transfer` function.
3890:   The input and output arrays passed to `transfer` are allocated by PETSc.
3891:   Vectors in `vecsout` must be created by the user.
3892:   Ownership of vectors in `vecsout` is transferred to PETSc.

3894:   Level: advanced

3896: .seealso: [](ch_ts), `TS`, `TSSetDM()`, `TSSetIJacobian()`, `TSSetRHSJacobian()`
3897: @*/
3898: PetscErrorCode TSSetResize(TS ts, PetscBool rollback, PetscErrorCode (*setup)(TS ts, PetscInt step, PetscReal time, Vec state, PetscBool *resize, PetscCtx ctx), PetscErrorCode (*transfer)(TS ts, PetscInt nv, Vec vecsin[], Vec vecsout[], PetscCtx ctx), PetscCtx ctx)
3899: {
3900:   PetscFunctionBegin;
3902:   ts->resizerollback = rollback;
3903:   ts->resizesetup    = setup;
3904:   ts->resizetransfer = transfer;
3905:   ts->resizectx      = ctx;
3906:   PetscFunctionReturn(PETSC_SUCCESS);
3907: }

3909: /*
3910:   TSResizeRegisterOrRetrieve - Register or import vectors transferred with `TSResize()`.

3912:   Collective

3914:   Input Parameters:
3915: + ts   - The `TS` context obtained from `TSCreate()`
3916: - flg - If `PETSC_TRUE` each TS implementation (e.g. `TSBDF`) will register vectors to be transferred, if `PETSC_FALSE` vectors will be imported from transferred vectors.

3918:   Level: developer

3920:   Note:
3921:   `TSResizeRegisterOrRetrieve()` is declared PETSC_INTERN since it is
3922:    used within time stepping implementations,
3923:    so most users would not generally call this routine themselves.

3925: .seealso: [](ch_ts), `TS`, `TSSetResize()`
3926: @*/
3927: static PetscErrorCode TSResizeRegisterOrRetrieve(TS ts, PetscBool flg)
3928: {
3929:   PetscFunctionBegin;
3931:   PetscTryTypeMethod(ts, resizeregister, flg);
3932:   /* PetscTryTypeMethod(adapt, resizeregister, flg); */
3933:   PetscFunctionReturn(PETSC_SUCCESS);
3934: }

3936: static PetscErrorCode TSResizeReset(TS ts)
3937: {
3938:   PetscFunctionBegin;
3940:   PetscCall(PetscObjectListDestroy(&ts->resizetransferobjs));
3941:   PetscFunctionReturn(PETSC_SUCCESS);
3942: }

3944: static PetscErrorCode TSResizeTransferVecs(TS ts, PetscInt cnt, Vec vecsin[], Vec vecsout[])
3945: {
3946:   PetscFunctionBegin;
3949:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPush(vecsin[i]));
3950:   if (ts->resizetransfer) {
3951:     PetscCall(PetscInfo(ts, "Transferring %" PetscInt_FMT " vectors\n", cnt));
3952:     PetscCallBack("TS callback resize transfer", (*ts->resizetransfer)(ts, cnt, vecsin, vecsout, ts->resizectx));
3953:   }
3954:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPop(vecsin[i]));
3955:   PetscFunctionReturn(PETSC_SUCCESS);
3956: }

3958: /*@
3959:   TSResizeRegisterVec - Register a vector to be transferred with `TSResize()`.

3961:   Collective

3963:   Input Parameters:
3964: + ts   - The `TS` context obtained from `TSCreate()`
3965: . name - A string identifying the vector
3966: - vec  - The vector

3968:   Level: developer

3970:   Note:
3971:   `TSResizeRegisterVec()` is typically used within time stepping implementations,
3972:   so most users would not generally call this routine themselves.

3974: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRetrieveVec()`
3975: @*/
3976: PetscErrorCode TSResizeRegisterVec(TS ts, const char name[], Vec vec)
3977: {
3978:   PetscFunctionBegin;
3980:   PetscAssertPointer(name, 2);
3982:   PetscCall(PetscObjectListAdd(&ts->resizetransferobjs, name, (PetscObject)vec));
3983:   PetscFunctionReturn(PETSC_SUCCESS);
3984: }

3986: /*@
3987:   TSResizeRetrieveVec - Retrieve a vector registered with `TSResizeRegisterVec()`.

3989:   Collective

3991:   Input Parameters:
3992: + ts   - The `TS` context obtained from `TSCreate()`
3993: . name - A string identifying the vector
3994: - vec  - The vector

3996:   Level: developer

3998:   Note:
3999:   `TSResizeRetrieveVec()` is typically used within time stepping implementations,
4000:   so most users would not generally call this routine themselves.

4002: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRegisterVec()`
4003: @*/
4004: PetscErrorCode TSResizeRetrieveVec(TS ts, const char name[], Vec *vec)
4005: {
4006:   PetscFunctionBegin;
4008:   PetscAssertPointer(name, 2);
4009:   PetscAssertPointer(vec, 3);
4010:   PetscCall(PetscObjectListFind(ts->resizetransferobjs, name, (PetscObject *)vec));
4011:   PetscFunctionReturn(PETSC_SUCCESS);
4012: }

4014: static PetscErrorCode TSResizeGetVecArray(TS ts, PetscInt *nv, const char **names[], Vec *vecs[])
4015: {
4016:   PetscInt        cnt;
4017:   PetscObjectList tmp;
4018:   Vec            *vecsin  = NULL;
4019:   const char    **namesin = NULL;

4021:   PetscFunctionBegin;
4022:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next)
4023:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) cnt++;
4024:   if (names) PetscCall(PetscMalloc1(cnt, &namesin));
4025:   if (vecs) PetscCall(PetscMalloc1(cnt, &vecsin));
4026:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next) {
4027:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) {
4028:       if (vecs) vecsin[cnt] = (Vec)tmp->obj;
4029:       if (names) namesin[cnt] = tmp->name;
4030:       cnt++;
4031:     }
4032:   }
4033:   if (nv) *nv = cnt;
4034:   if (names) *names = namesin;
4035:   if (vecs) *vecs = vecsin;
4036:   PetscFunctionReturn(PETSC_SUCCESS);
4037: }

4039: /*@
4040:   TSResize - Runs the user-defined transfer functions provided with `TSSetResize()`

4042:   Collective

4044:   Input Parameter:
4045: . ts - The `TS` context obtained from `TSCreate()`

4047:   Level: developer

4049:   Note:
4050:   `TSResize()` is typically used within time stepping implementations,
4051:   so most users would not generally call this routine themselves.

4053: .seealso: [](ch_ts), `TS`, `TSSetResize()`
4054: @*/
4055: PetscErrorCode TSResize(TS ts)
4056: {
4057:   PetscInt     nv      = 0;
4058:   const char **names   = NULL;
4059:   Vec         *vecsin  = NULL;
4060:   const char  *solname = "ts:vec_sol";

4062:   PetscFunctionBegin;
4064:   if (!ts->resizesetup) PetscFunctionReturn(PETSC_SUCCESS);
4065:   if (ts->resizesetup) {
4066:     PetscCall(VecLockReadPush(ts->vec_sol));
4067:     PetscCallBack("TS callback resize setup", (*ts->resizesetup)(ts, ts->steps, ts->ptime, ts->vec_sol, &ts->stepresize, ts->resizectx));
4068:     PetscCall(VecLockReadPop(ts->vec_sol));
4069:     if (ts->stepresize) {
4070:       if (ts->resizerollback) {
4071:         PetscCall(TSRollBack(ts));
4072:         ts->time_step = ts->time_step0;
4073:       }
4074:       PetscCall(TSResizeRegisterVec(ts, solname, ts->vec_sol));
4075:       PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_TRUE)); /* specific impls register their own objects */
4076:     }
4077:   }

4079:   PetscCall(TSResizeGetVecArray(ts, &nv, &names, &vecsin));
4080:   if (nv) {
4081:     Vec *vecsout, vecsol;

4083:     /* Reset internal objects */
4084:     PetscCall(TSReset(ts));

4086:     /* Transfer needed vectors (users can call SetJacobian, SetDM, etc. here) */
4087:     PetscCall(PetscCalloc1(nv, &vecsout));
4088:     PetscCall(TSResizeTransferVecs(ts, nv, vecsin, vecsout));
4089:     for (PetscInt i = 0; i < nv; i++) {
4090:       const char *name;
4091:       char       *oname;

4093:       PetscCall(PetscObjectGetName((PetscObject)vecsin[i], &name));
4094:       PetscCall(PetscStrallocpy(name, &oname));
4095:       PetscCall(TSResizeRegisterVec(ts, names[i], vecsout[i]));
4096:       if (vecsout[i]) PetscCall(PetscObjectSetName((PetscObject)vecsout[i], oname));
4097:       PetscCall(PetscFree(oname));
4098:       PetscCall(VecDestroy(&vecsout[i]));
4099:     }
4100:     PetscCall(PetscFree(vecsout));
4101:     PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_FALSE)); /* specific impls import the transferred objects */

4103:     PetscCall(TSResizeRetrieveVec(ts, solname, &vecsol));
4104:     if (vecsol) PetscCall(TSSetSolution(ts, vecsol));
4105:     PetscAssert(ts->vec_sol, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_NULL, "Missing TS solution");
4106:   }

4108:   PetscCall(PetscFree(names));
4109:   PetscCall(PetscFree(vecsin));
4110:   PetscCall(TSResizeReset(ts));
4111:   PetscFunctionReturn(PETSC_SUCCESS);
4112: }

4114: /*@
4115:   TSSolve - Steps the requested number of timesteps.

4117:   Collective

4119:   Input Parameters:
4120: + ts - the `TS` context obtained from `TSCreate()`
4121: - u  - the solution vector  (can be `NULL` if `TSSetSolution()` was used and `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`) was not used,
4122:        otherwise it must contain the initial conditions and will contain the solution at the final requested time

4124:   Level: beginner

4126:   Note:
4127:   The final time returned by this function may be different from the time of the internally
4128:   held state accessible by `TSGetSolution()` and `TSGetTime()` because the method may have
4129:   stepped over the final time.

4131: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetSolution()`, `TSStep()`, `TSGetTime()`, `TSGetSolveTime()`
4132: @*/
4133: PetscErrorCode TSSolve(TS ts, Vec u)
4134: {
4135:   Vec solution;

4137:   PetscFunctionBegin;

4141:   PetscCall(TSSetExactFinalTimeDefault(ts));
4142:   if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE && u) { /* Need ts->vec_sol to be distinct so it is not overwritten when we interpolate at the end */
4143:     if (!ts->vec_sol || u == ts->vec_sol) {
4144:       PetscCall(VecDuplicate(u, &solution));
4145:       PetscCall(TSSetSolution(ts, solution));
4146:       PetscCall(VecDestroy(&solution)); /* grant ownership */
4147:     }
4148:     PetscCall(VecCopy(u, ts->vec_sol));
4149:     PetscCheck(!ts->forward_solve, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Sensitivity analysis does not support the mode TS_EXACTFINALTIME_INTERPOLATE");
4150:   } else if (u) PetscCall(TSSetSolution(ts, u));
4151:   PetscCall(TSSetUp(ts));
4152:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));

4154:   PetscCheck(ts->max_time < PETSC_MAX_REAL || ts->run_steps != PETSC_INT_MAX || ts->max_steps != PETSC_INT_MAX, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetMaxTime(), TSSetMaxSteps(), or TSSetRunSteps() or use -ts_max_time <time>, -ts_max_steps <steps>, -ts_run_steps <steps>");
4155:   PetscCheck(ts->exact_final_time != TS_EXACTFINALTIME_UNSPECIFIED, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetExactFinalTime() or use -ts_exact_final_time <stepover,interpolate,matchstep> before calling TSSolve()");
4156:   PetscCheck(ts->exact_final_time != TS_EXACTFINALTIME_MATCHSTEP || ts->adapt, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Since TS is not adaptive you cannot use TS_EXACTFINALTIME_MATCHSTEP, suggest TS_EXACTFINALTIME_INTERPOLATE");
4157:   PetscCheck(!(ts->eval_times && ts->exact_final_time != TS_EXACTFINALTIME_MATCHSTEP), PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "You must use TS_EXACTFINALTIME_MATCHSTEP when using time span or evaluation times");

4159:   if (ts->eval_times) {
4160:     if (!ts->eval_times->sol_vecs) PetscCall(VecDuplicateVecs(ts->vec_sol, ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
4161:     for (PetscInt i = 0; i < ts->eval_times->num_time_points; i++) {
4162:       PetscBool is_close = PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[i], ts->eval_times->reltol * ts->time_step + ts->eval_times->abstol, 0);
4163:       if (ts->ptime <= ts->eval_times->time_points[i] || is_close) {
4164:         ts->eval_times->time_point_idx = i;

4166:         PetscBool is_ptime_in_sol_times = PETSC_FALSE; // If current solution has already been saved, we should not save it again
4167:         if (ts->eval_times->sol_idx > 0) is_ptime_in_sol_times = PetscIsCloseAtTol(ts->ptime, ts->eval_times->sol_times[ts->eval_times->sol_idx - 1], ts->eval_times->reltol * ts->time_step + ts->eval_times->abstol, 0);
4168:         if (is_close && !is_ptime_in_sol_times) {
4169:           PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_idx]));
4170:           ts->eval_times->sol_times[ts->eval_times->sol_idx] = ts->ptime;
4171:           ts->eval_times->sol_idx++;
4172:           ts->eval_times->time_point_idx++;
4173:         }
4174:         break;
4175:       }
4176:     }
4177:   }

4179:   if (ts->forward_solve) PetscCall(TSForwardSetUp(ts));

4181:   /* reset number of steps only when the step is not restarted. ARKIMEX
4182:      restarts the step after an event. Resetting these counters in such case causes
4183:      TSTrajectory to incorrectly save the output files
4184:   */
4185:   /* reset time step and iteration counters */
4186:   if (!ts->steps) {
4187:     ts->ksp_its           = 0;
4188:     ts->snes_its          = 0;
4189:     ts->num_snes_failures = 0;
4190:     ts->reject            = 0;
4191:     ts->steprestart       = PETSC_TRUE;
4192:     ts->steprollback      = PETSC_FALSE;
4193:     ts->stepresize        = PETSC_FALSE;
4194:     ts->rhsjacobian.time  = PETSC_MIN_REAL;
4195:   }

4197:   /* make sure initial time step does not overshoot final time or the next point in evaluation times */
4198:   if (ts->exact_final_time == TS_EXACTFINALTIME_MATCHSTEP) {
4199:     PetscReal maxdt;
4200:     PetscReal dt = ts->time_step;

4202:     if (ts->eval_times) maxdt = ts->eval_times->time_points[ts->eval_times->time_point_idx] - ts->ptime;
4203:     else maxdt = ts->max_time - ts->ptime;
4204:     ts->time_step = dt >= maxdt ? maxdt : (PetscIsCloseAtTol(dt, maxdt, 10 * PETSC_MACHINE_EPSILON, 0) ? maxdt : dt);
4205:   }
4206:   ts->reason = TS_CONVERGED_ITERATING;

4208:   {
4209:     PetscViewer       viewer;
4210:     PetscViewerFormat format;
4211:     PetscBool         flg;
4212:     static PetscBool  incall = PETSC_FALSE;

4214:     if (!incall) {
4215:       /* Estimate the convergence rate of the time discretization */
4216:       PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)ts), ((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_estimate", &viewer, &format, &flg));
4217:       if (flg) {
4218:         PetscConvEst conv;
4219:         DM           dm;
4220:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4221:         PetscInt     Nf;
4222:         PetscBool    checkTemporal = PETSC_TRUE;

4224:         incall = PETSC_TRUE;
4225:         PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_temporal", &checkTemporal, &flg));
4226:         PetscCall(TSGetDM(ts, &dm));
4227:         PetscCall(DMGetNumFields(dm, &Nf));
4228:         PetscCall(PetscCalloc1(PetscMax(Nf, 1), &alpha));
4229:         PetscCall(PetscConvEstCreate(PetscObjectComm((PetscObject)ts), &conv));
4230:         PetscCall(PetscConvEstUseTS(conv, checkTemporal));
4231:         PetscCall(PetscConvEstSetSolver(conv, (PetscObject)ts));
4232:         PetscCall(PetscConvEstSetFromOptions(conv));
4233:         PetscCall(PetscConvEstSetUp(conv));
4234:         PetscCall(PetscConvEstGetConvRate(conv, alpha));
4235:         PetscCall(PetscViewerPushFormat(viewer, format));
4236:         PetscCall(PetscConvEstRateView(conv, alpha, viewer));
4237:         PetscCall(PetscViewerPopFormat(viewer));
4238:         PetscCall(PetscViewerDestroy(&viewer));
4239:         PetscCall(PetscConvEstDestroy(&conv));
4240:         PetscCall(PetscFree(alpha));
4241:         incall = PETSC_FALSE;
4242:       }
4243:     }
4244:   }

4246:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view_pre"));

4248:   if (ts->ops->solve) { /* This private interface is transitional and should be removed when all implementations are updated. */
4249:     PetscUseTypeMethod(ts, solve);
4250:     if (u) PetscCall(VecCopy(ts->vec_sol, u));
4251:     ts->solvetime = ts->ptime;
4252:     solution      = ts->vec_sol;
4253:   } else { /* Step the requested number of timesteps. */
4254:     if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4255:     else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;

4257:     if (!ts->steps) {
4258:       PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4259:       PetscCall(TSEventInitialize(ts->event, ts, ts->ptime, ts->vec_sol));
4260:     }

4262:     ts->start_step = ts->steps; // records starting step
4263:     while (!ts->reason) {
4264:       PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));
4265:       if (!ts->steprollback || (ts->stepresize && ts->resizerollback)) PetscCall(TSPreStep(ts));
4266:       PetscCall(TSStep(ts));
4267:       if (ts->testjacobian) PetscCall(TSRHSJacobianTest(ts, NULL));
4268:       if (ts->testjacobiantranspose) PetscCall(TSRHSJacobianTestTranspose(ts, NULL));
4269:       if (ts->quadraturets && ts->costintegralfwd) { /* Must evaluate the cost integral before event is handled. The cost integral value can also be rolled back. */
4270:         if (ts->reason >= 0) ts->steps--;            /* Revert the step number changed by TSStep() */
4271:         PetscCall(TSForwardCostIntegral(ts));
4272:         if (ts->reason >= 0) ts->steps++;
4273:       }
4274:       if (ts->forward_solve) {            /* compute forward sensitivities before event handling because postevent() may change RHS and jump conditions may have to be applied */
4275:         if (ts->reason >= 0) ts->steps--; /* Revert the step number changed by TSStep() */
4276:         PetscCall(TSForwardStep(ts));
4277:         if (ts->reason >= 0) ts->steps++;
4278:       }
4279:       PetscCall(TSPostEvaluate(ts));
4280:       PetscCall(TSEventHandler(ts)); /* The right-hand side may be changed due to event. Be careful with Any computation using the RHS information after this point. */
4281:       if (ts->steprollback) PetscCall(TSPostEvaluate(ts));
4282:       if (!ts->steprollback && ts->resizerollback) PetscCall(TSResize(ts));
4283:       /* check convergence */
4284:       if (!ts->reason) {
4285:         if ((ts->steps - ts->start_step) >= ts->run_steps) ts->reason = TS_CONVERGED_ITS;
4286:         else if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4287:         else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;
4288:       }
4289:       if (!ts->steprollback) {
4290:         PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4291:         PetscCall(TSPostStep(ts));
4292:         if (!ts->resizerollback) PetscCall(TSResize(ts));

4294:         if (ts->eval_times && ts->eval_times->time_point_idx < ts->eval_times->num_time_points && ts->reason >= 0) {
4295:           PetscCheck(ts->eval_times->worktol > 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_PLIB, "Unexpected state !(eval_times->worktol > 0) in TSSolve()");
4296:           if (PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[ts->eval_times->time_point_idx], ts->eval_times->worktol, 0)) {
4297:             ts->eval_times->sol_times[ts->eval_times->sol_idx] = ts->ptime;
4298:             PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_idx]));
4299:             ts->eval_times->sol_idx++;
4300:             ts->eval_times->time_point_idx++;
4301:           }
4302:         }
4303:       }
4304:     }
4305:     PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));

4307:     if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE && ts->ptime > ts->max_time) {
4308:       if (!u) u = ts->vec_sol;
4309:       PetscCall(TSInterpolate(ts, ts->max_time, u));
4310:       ts->solvetime = ts->max_time;
4311:       solution      = u;
4312:       PetscCall(TSMonitor(ts, -1, ts->solvetime, solution));
4313:     } else {
4314:       if (u) PetscCall(VecCopy(ts->vec_sol, u));
4315:       ts->solvetime = ts->ptime;
4316:       solution      = ts->vec_sol;
4317:     }
4318:   }

4320:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view"));
4321:   PetscCall(VecViewFromOptions(solution, (PetscObject)ts, "-ts_view_solution"));
4322:   PetscCall(PetscObjectSAWsBlock((PetscObject)ts));
4323:   if (ts->adjoint_solve) PetscCall(TSAdjointSolve(ts));
4324:   PetscFunctionReturn(PETSC_SUCCESS);
4325: }

4327: /*@
4328:   TSGetTime - Gets the time of the most recently completed step.

4330:   Not Collective

4332:   Input Parameter:
4333: . ts - the `TS` context obtained from `TSCreate()`

4335:   Output Parameter:
4336: . t - the current time. This time may not corresponds to the final time set with `TSSetMaxTime()`, use `TSGetSolveTime()`.

4338:   Level: beginner

4340:   Note:
4341:   When called during time step evaluation (e.g. during residual evaluation or via hooks set using `TSSetPreStep()`,
4342:   `TSSetPreStage()`, `TSSetPostStage()`, or `TSSetPostStep()`), the time is the time at the start of the step being evaluated.

4344: .seealso: [](ch_ts), `TS`, `TSGetSolveTime()`, `TSSetTime()`, `TSGetTimeStep()`, `TSGetStepNumber()`
4345: @*/
4346: PetscErrorCode TSGetTime(TS ts, PetscReal *t)
4347: {
4348:   PetscFunctionBegin;
4350:   PetscAssertPointer(t, 2);
4351:   *t = ts->ptime;
4352:   PetscFunctionReturn(PETSC_SUCCESS);
4353: }

4355: /*@
4356:   TSGetPrevTime - Gets the starting time of the previously completed step.

4358:   Not Collective

4360:   Input Parameter:
4361: . ts - the `TS` context obtained from `TSCreate()`

4363:   Output Parameter:
4364: . t - the previous time

4366:   Level: beginner

4368: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetTimeStep()`
4369: @*/
4370: PetscErrorCode TSGetPrevTime(TS ts, PetscReal *t)
4371: {
4372:   PetscFunctionBegin;
4374:   PetscAssertPointer(t, 2);
4375:   *t = ts->ptime_prev;
4376:   PetscFunctionReturn(PETSC_SUCCESS);
4377: }

4379: /*@
4380:   TSSetTime - Allows one to reset the time.

4382:   Logically Collective

4384:   Input Parameters:
4385: + ts - the `TS` context obtained from `TSCreate()`
4386: - t  - the time

4388:   Level: intermediate

4390: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSSetMaxSteps()`
4391: @*/
4392: PetscErrorCode TSSetTime(TS ts, PetscReal t)
4393: {
4394:   PetscFunctionBegin;
4397:   ts->ptime = t;
4398:   PetscFunctionReturn(PETSC_SUCCESS);
4399: }

4401: /*@
4402:   TSSetOptionsPrefix - Sets the prefix used for searching for all
4403:   TS options in the database.

4405:   Logically Collective

4407:   Input Parameters:
4408: + ts     - The `TS` context
4409: - prefix - The prefix to prepend to all option names

4411:   Level: advanced

4413:   Note:
4414:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4415:   The first character of all runtime options is AUTOMATICALLY the
4416:   hyphen.

4418: .seealso: [](ch_ts), `TS`, `TSSetFromOptions()`, `TSAppendOptionsPrefix()`
4419: @*/
4420: PetscErrorCode TSSetOptionsPrefix(TS ts, const char prefix[])
4421: {
4422:   SNES snes;

4424:   PetscFunctionBegin;
4426:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)ts, prefix));
4427:   PetscCall(TSGetSNES(ts, &snes));
4428:   PetscCall(SNESSetOptionsPrefix(snes, prefix));
4429:   PetscFunctionReturn(PETSC_SUCCESS);
4430: }

4432: /*@
4433:   TSAppendOptionsPrefix - Appends to the prefix used for searching for all
4434:   TS options in the database.

4436:   Logically Collective

4438:   Input Parameters:
4439: + ts     - The `TS` context
4440: - prefix - The prefix to prepend to all option names

4442:   Level: advanced

4444:   Note:
4445:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4446:   The first character of all runtime options is AUTOMATICALLY the
4447:   hyphen.

4449: .seealso: [](ch_ts), `TS`, `TSGetOptionsPrefix()`, `TSSetOptionsPrefix()`, `TSSetFromOptions()`
4450: @*/
4451: PetscErrorCode TSAppendOptionsPrefix(TS ts, const char prefix[])
4452: {
4453:   SNES snes;

4455:   PetscFunctionBegin;
4457:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)ts, prefix));
4458:   PetscCall(TSGetSNES(ts, &snes));
4459:   PetscCall(SNESAppendOptionsPrefix(snes, prefix));
4460:   PetscFunctionReturn(PETSC_SUCCESS);
4461: }

4463: /*@
4464:   TSGetOptionsPrefix - Sets the prefix used for searching for all
4465:   `TS` options in the database.

4467:   Not Collective

4469:   Input Parameter:
4470: . ts - The `TS` context

4472:   Output Parameter:
4473: . prefix - A pointer to the prefix string used

4475:   Level: intermediate

4477: .seealso: [](ch_ts), `TS`, `TSAppendOptionsPrefix()`, `TSSetFromOptions()`
4478: @*/
4479: PetscErrorCode TSGetOptionsPrefix(TS ts, const char *prefix[])
4480: {
4481:   PetscFunctionBegin;
4483:   PetscAssertPointer(prefix, 2);
4484:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ts, prefix));
4485:   PetscFunctionReturn(PETSC_SUCCESS);
4486: }

4488: /*@
4489:   TSGetRHSJacobian - Returns the Jacobian J at the present timestep.

4491:   Not Collective, but parallel objects are returned if ts is parallel

4493:   Input Parameter:
4494: . ts - The `TS` context obtained from `TSCreate()`

4496:   Output Parameters:
4497: + Amat - The (approximate) Jacobian J of G, where U_t = G(U,t)  (or `NULL`)
4498: . Pmat - The matrix from which the preconditioner is constructed, usually the same as `Amat`  (or `NULL`)
4499: . func - Function to compute the Jacobian of the RHS  (or `NULL`)
4500: - ctx  - User-defined context for Jacobian evaluation routine  (or `NULL`)

4502:   Level: intermediate

4504:   Note:
4505:   You can pass in `NULL` for any return argument you do not need.

4507: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`
4508: @*/
4509: PetscErrorCode TSGetRHSJacobian(TS ts, Mat *Amat, Mat *Pmat, TSRHSJacobianFn **func, PetscCtxRt ctx)
4510: {
4511:   DM dm;

4513:   PetscFunctionBegin;
4514:   if (Amat || Pmat) {
4515:     SNES snes;
4516:     PetscCall(TSGetSNES(ts, &snes));
4517:     PetscCall(SNESSetUpMatrices(snes));
4518:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4519:   }
4520:   PetscCall(TSGetDM(ts, &dm));
4521:   PetscCall(DMTSGetRHSJacobian(dm, func, ctx));
4522:   PetscFunctionReturn(PETSC_SUCCESS);
4523: }

4525: /*@
4526:   TSGetIJacobian - Returns the implicit Jacobian at the present timestep.

4528:   Not Collective, but parallel objects are returned if ts is parallel

4530:   Input Parameter:
4531: . ts - The `TS` context obtained from `TSCreate()`

4533:   Output Parameters:
4534: + Amat - The (approximate) Jacobian of F(t,U,U_t)
4535: . Pmat - The matrix from which the preconditioner is constructed, often the same as `Amat`
4536: . f    - The function to compute the matrices
4537: - ctx  - User-defined context for Jacobian evaluation routine

4539:   Level: advanced

4541:   Note:
4542:   You can pass in `NULL` for any return argument you do not need.

4544: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetRHSJacobian()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`
4545: @*/
4546: PetscErrorCode TSGetIJacobian(TS ts, Mat *Amat, Mat *Pmat, TSIJacobianFn **f, PetscCtxRt ctx)
4547: {
4548:   DM dm;

4550:   PetscFunctionBegin;
4551:   if (Amat || Pmat) {
4552:     SNES snes;
4553:     PetscCall(TSGetSNES(ts, &snes));
4554:     PetscCall(SNESSetUpMatrices(snes));
4555:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4556:   }
4557:   PetscCall(TSGetDM(ts, &dm));
4558:   PetscCall(DMTSGetIJacobian(dm, f, ctx));
4559:   PetscFunctionReturn(PETSC_SUCCESS);
4560: }

4562: #include <petsc/private/dmimpl.h>
4563: /*@
4564:   TSSetDM - Sets the `DM` that may be used by some nonlinear solvers or preconditioners under the `TS`

4566:   Logically Collective

4568:   Input Parameters:
4569: + ts - the `TS` integrator object
4570: - dm - the dm, cannot be `NULL`

4572:   Level: intermediate

4574:   Notes:
4575:   A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
4576:   even when not using interfaces like `DMTSSetIFunction()`.  Use `DMClone()` to get a distinct `DM` when solving
4577:   different problems using the same function space.

4579: .seealso: [](ch_ts), `TS`, `DM`, `TSGetDM()`, `SNESSetDM()`, `SNESGetDM()`
4580: @*/
4581: PetscErrorCode TSSetDM(TS ts, DM dm)
4582: {
4583:   SNES snes;
4584:   DMTS tsdm;

4586:   PetscFunctionBegin;
4589:   PetscCall(PetscObjectReference((PetscObject)dm));
4590:   if (ts->dm) { /* Move the DMTS context over to the new DM unless the new DM already has one */
4591:     if (ts->dm->dmts && !dm->dmts) {
4592:       PetscCall(DMCopyDMTS(ts->dm, dm));
4593:       PetscCall(DMGetDMTS(ts->dm, &tsdm));
4594:       /* Grant write privileges to the replacement DM */
4595:       if (tsdm->originaldm == ts->dm) tsdm->originaldm = dm;
4596:     }
4597:     PetscCall(DMDestroy(&ts->dm));
4598:   }
4599:   ts->dm = dm;

4601:   PetscCall(TSGetSNES(ts, &snes));
4602:   PetscCall(SNESSetDM(snes, dm));
4603:   PetscFunctionReturn(PETSC_SUCCESS);
4604: }

4606: /*@
4607:   TSGetDM - Gets the `DM` that may be used by some preconditioners

4609:   Not Collective

4611:   Input Parameter:
4612: . ts - the `TS`

4614:   Output Parameter:
4615: . dm - the `DM`

4617:   Level: intermediate

4619: .seealso: [](ch_ts), `TS`, `DM`, `TSSetDM()`, `SNESSetDM()`, `SNESGetDM()`
4620: @*/
4621: PetscErrorCode TSGetDM(TS ts, DM *dm)
4622: {
4623:   PetscFunctionBegin;
4625:   if (!ts->dm) {
4626:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)ts), &ts->dm));
4627:     if (ts->snes) PetscCall(SNESSetDM(ts->snes, ts->dm));
4628:   }
4629:   *dm = ts->dm;
4630:   PetscFunctionReturn(PETSC_SUCCESS);
4631: }

4633: /*@
4634:   SNESTSFormFunction - Function to evaluate nonlinear residual defined by an ODE solver algorithm implemented within `TS`

4636:   Logically Collective

4638:   Input Parameters:
4639: + snes - nonlinear solver
4640: . U    - the current state at which to evaluate the residual
4641: - ctx  - application context, must be a `TS`

4643:   Output Parameter:
4644: . F - the nonlinear residual

4646:   Level: developer

4648:   Note:
4649:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.
4650:   It is most frequently passed to `MatFDColoringSetFunction()`.

4652: .seealso: [](ch_ts), `SNESSetFunction()`, `MatFDColoringSetFunction()`
4653: @*/
4654: PetscErrorCode SNESTSFormFunction(SNES snes, Vec U, Vec F, PetscCtx ctx)
4655: {
4656:   TS ts = (TS)ctx;

4658:   PetscFunctionBegin;
4663:   PetscCheck(ts->ops->snesfunction, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesfunction for TS of type %s", ((PetscObject)ts)->type_name);
4664:   PetscCall((*ts->ops->snesfunction)(snes, U, F, ts));
4665:   PetscFunctionReturn(PETSC_SUCCESS);
4666: }

4668: /*@
4669:   SNESTSFormJacobian - Function to evaluate the Jacobian defined by an ODE solver algorithm implemented within `TS`

4671:   Collective

4673:   Input Parameters:
4674: + snes - nonlinear solver
4675: . U    - the current state at which to evaluate the residual
4676: - ctx  - application context, must be a `TS`

4678:   Output Parameters:
4679: + A - the Jacobian
4680: - B - the matrix used to construct the preconditioner (often the same as `A`)

4682:   Level: developer

4684:   Note:
4685:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.

4687: .seealso: [](ch_ts), `SNESSetJacobian()`
4688: @*/
4689: PetscErrorCode SNESTSFormJacobian(SNES snes, Vec U, Mat A, Mat B, PetscCtx ctx)
4690: {
4691:   TS ts = (TS)ctx;

4693:   PetscFunctionBegin;
4699:   PetscCheck(ts->ops->snesjacobian, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesjacobian for TS of type %s", ((PetscObject)ts)->type_name);
4700:   PetscCall((*ts->ops->snesjacobian)(snes, U, A, B, ts));
4701:   PetscFunctionReturn(PETSC_SUCCESS);
4702: }

4704: /*@
4705:   TSComputeRHSFunctionLinear - Evaluate the right-hand side via the user-provided Jacobian, for linear problems Udot = A U only

4707:   Collective

4709:   Input Parameters:
4710: + ts  - time stepping context
4711: . t   - time at which to evaluate
4712: . U   - state at which to evaluate
4713: - ctx - context

4715:   Output Parameter:
4716: . F - right-hand side

4718:   Level: intermediate

4720:   Note:
4721:   This function is intended to be passed to `TSSetRHSFunction()` to evaluate the right-hand side for linear problems.
4722:   The matrix (and optionally the evaluation context) should be passed to `TSSetRHSJacobian()`.

4724: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
4725: @*/
4726: PetscErrorCode TSComputeRHSFunctionLinear(TS ts, PetscReal t, Vec U, Vec F, PetscCtx ctx)
4727: {
4728:   Mat Arhs, Brhs;

4730:   PetscFunctionBegin;
4731:   PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
4732:   /* undo the damage caused by shifting */
4733:   PetscCall(TSRecoverRHSJacobian(ts, Arhs, Brhs));
4734:   PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
4735:   PetscCall(MatMult(Arhs, U, F));
4736:   PetscFunctionReturn(PETSC_SUCCESS);
4737: }

4739: /*@
4740:   TSComputeRHSJacobianConstant - Reuses a Jacobian that is time-independent.

4742:   Collective

4744:   Input Parameters:
4745: + ts  - time stepping context
4746: . t   - time at which to evaluate
4747: . U   - state at which to evaluate
4748: - ctx - context

4750:   Output Parameters:
4751: + A - Jacobian
4752: - B - matrix used to construct the preconditioner, often the same as `A`

4754:   Level: intermediate

4756:   Note:
4757:   This function is intended to be passed to `TSSetRHSJacobian()` to evaluate the Jacobian for linear time-independent problems.

4759: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSFunctionLinear()`
4760: @*/
4761: PetscErrorCode TSComputeRHSJacobianConstant(TS ts, PetscReal t, Vec U, Mat A, Mat B, PetscCtx ctx)
4762: {
4763:   PetscFunctionBegin;
4764:   PetscFunctionReturn(PETSC_SUCCESS);
4765: }

4767: /*@
4768:   TSComputeIFunctionLinear - Evaluate the left hand side via the user-provided Jacobian, for linear problems only

4770:   Collective

4772:   Input Parameters:
4773: + ts   - time stepping context
4774: . t    - time at which to evaluate
4775: . U    - state at which to evaluate
4776: . Udot - time derivative of state vector
4777: - ctx  - context

4779:   Output Parameter:
4780: . F - left hand side

4782:   Level: intermediate

4784:   Notes:
4785:   The assumption here is that the left hand side is of the form A*Udot (and not A*Udot + B*U). For other cases, the
4786:   user is required to write their own `TSComputeIFunction()`.
4787:   This function is intended to be passed to `TSSetIFunction()` to evaluate the left hand side for linear problems.
4788:   The matrix (and optionally the evaluation context) should be passed to `TSSetIJacobian()`.

4790:   Note that using this function is NOT equivalent to using `TSComputeRHSFunctionLinear()` since that solves Udot = A U

4792: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIJacobianConstant()`, `TSComputeRHSFunctionLinear()`
4793: @*/
4794: PetscErrorCode TSComputeIFunctionLinear(TS ts, PetscReal t, Vec U, Vec Udot, Vec F, PetscCtx ctx)
4795: {
4796:   Mat A, B;

4798:   PetscFunctionBegin;
4799:   PetscCall(TSGetIJacobian(ts, &A, &B, NULL, NULL));
4800:   PetscCall(TSComputeIJacobian(ts, t, U, Udot, 1.0, A, B, PETSC_TRUE));
4801:   PetscCall(MatMult(A, Udot, F));
4802:   PetscFunctionReturn(PETSC_SUCCESS);
4803: }

4805: /*@
4806:   TSComputeIJacobianConstant - Reuses the matrix previously computed with the provided `TSIJacobianFn` for a semi-implicit DAE or ODE

4808:   Collective

4810:   Input Parameters:
4811: + ts    - time stepping context
4812: . t     - time at which to evaluate
4813: . U     - state at which to evaluate
4814: . Udot  - time derivative of state vector
4815: . shift - shift to apply
4816: - ctx   - context

4818:   Output Parameters:
4819: + A - pointer to operator
4820: - B - pointer to matrix from which the preconditioner is built (often `A`)

4822:   Level: advanced

4824:   Notes:
4825:   This function is intended to be passed to `TSSetIJacobian()` to evaluate the Jacobian for linear time-independent problems.

4827:   It is only appropriate for problems of the form

4829:   $$
4830:   M \dot{U} = F(U,t)
4831:   $$

4833:   where M is constant and F is non-stiff.  The user must pass M to `TSSetIJacobian()`.  The current implementation only
4834:   works with IMEX time integration methods such as `TSROSW` and `TSARKIMEX`, since there is no support for de-constructing
4835:   an implicit operator of the form

4837:   $$
4838:   shift*M + J
4839:   $$

4841:   where J is the Jacobian of -F(U).  Support may be added in a future version of PETSc, but for now, the user must store
4842:   a copy of M or reassemble it when requested.

4844: .seealso: [](ch_ts), `TS`, `TSROSW`, `TSARKIMEX`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIFunctionLinear()`
4845: @*/
4846: PetscErrorCode TSComputeIJacobianConstant(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, PetscCtx ctx)
4847: {
4848:   PetscFunctionBegin;
4849:   PetscCall(MatScale(A, shift / ts->ijacobian.shift));
4850:   ts->ijacobian.shift = shift;
4851:   PetscFunctionReturn(PETSC_SUCCESS);
4852: }

4854: /*@
4855:   TSGetEquationType - Gets the type of the equation that `TS` is solving.

4857:   Not Collective

4859:   Input Parameter:
4860: . ts - the `TS` context

4862:   Output Parameter:
4863: . equation_type - see `TSEquationType`

4865:   Level: beginner

4867: .seealso: [](ch_ts), `TS`, `TSSetEquationType()`, `TSEquationType`
4868: @*/
4869: PetscErrorCode TSGetEquationType(TS ts, TSEquationType *equation_type)
4870: {
4871:   PetscFunctionBegin;
4873:   PetscAssertPointer(equation_type, 2);
4874:   *equation_type = ts->equation_type;
4875:   PetscFunctionReturn(PETSC_SUCCESS);
4876: }

4878: /*@
4879:   TSSetEquationType - Sets the type of the equation that `TS` is solving.

4881:   Not Collective

4883:   Input Parameters:
4884: + ts            - the `TS` context
4885: - equation_type - see `TSEquationType`

4887:   Level: advanced

4889: .seealso: [](ch_ts), `TS`, `TSGetEquationType()`, `TSEquationType`
4890: @*/
4891: PetscErrorCode TSSetEquationType(TS ts, TSEquationType equation_type)
4892: {
4893:   PetscFunctionBegin;
4895:   ts->equation_type = equation_type;
4896:   PetscFunctionReturn(PETSC_SUCCESS);
4897: }

4899: /*@
4900:   TSGetConvergedReason - Gets the reason the `TS` iteration was stopped.

4902:   Not Collective

4904:   Input Parameter:
4905: . ts - the `TS` context

4907:   Output Parameter:
4908: . reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4909:             manual pages for the individual convergence tests for complete lists

4911:   Level: beginner

4913:   Note:
4914:   Can only be called after the call to `TSSolve()` is complete.

4916: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4917: @*/
4918: PetscErrorCode TSGetConvergedReason(TS ts, TSConvergedReason *reason)
4919: {
4920:   PetscFunctionBegin;
4922:   PetscAssertPointer(reason, 2);
4923:   *reason = ts->reason;
4924:   PetscFunctionReturn(PETSC_SUCCESS);
4925: }

4927: /*@
4928:   TSSetConvergedReason - Sets the reason for handling the convergence of `TSSolve()`.

4930:   Logically Collective; reason must contain common value

4932:   Input Parameters:
4933: + ts     - the `TS` context
4934: - reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4935:             manual pages for the individual convergence tests for complete lists

4937:   Level: advanced

4939:   Note:
4940:   Can only be called while `TSSolve()` is active.

4942: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4943: @*/
4944: PetscErrorCode TSSetConvergedReason(TS ts, TSConvergedReason reason)
4945: {
4946:   PetscFunctionBegin;
4948:   ts->reason = reason;
4949:   PetscFunctionReturn(PETSC_SUCCESS);
4950: }

4952: /*@
4953:   TSGetSolveTime - Gets the time after a call to `TSSolve()`

4955:   Not Collective

4957:   Input Parameter:
4958: . ts - the `TS` context

4960:   Output Parameter:
4961: . ftime - the final time. This time corresponds to the final time set with `TSSetMaxTime()`

4963:   Level: beginner

4965:   Note:
4966:   Can only be called after the call to `TSSolve()` is complete.

4968: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4969: @*/
4970: PetscErrorCode TSGetSolveTime(TS ts, PetscReal *ftime)
4971: {
4972:   PetscFunctionBegin;
4974:   PetscAssertPointer(ftime, 2);
4975:   *ftime = ts->solvetime;
4976:   PetscFunctionReturn(PETSC_SUCCESS);
4977: }

4979: /*@
4980:   TSGetSNESIterations - Gets the total number of nonlinear iterations
4981:   used by the time integrator.

4983:   Not Collective

4985:   Input Parameter:
4986: . ts - `TS` context

4988:   Output Parameter:
4989: . nits - number of nonlinear iterations

4991:   Level: intermediate

4993:   Note:
4994:   This counter is reset to zero for each successive call to `TSSolve()`.

4996: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetKSPIterations()`
4997: @*/
4998: PetscErrorCode TSGetSNESIterations(TS ts, PetscInt *nits)
4999: {
5000:   PetscFunctionBegin;
5002:   PetscAssertPointer(nits, 2);
5003:   *nits = ts->snes_its;
5004:   PetscFunctionReturn(PETSC_SUCCESS);
5005: }

5007: /*@
5008:   TSGetKSPIterations - Gets the total number of linear iterations
5009:   used by the time integrator.

5011:   Not Collective

5013:   Input Parameter:
5014: . ts - `TS` context

5016:   Output Parameter:
5017: . lits - number of linear iterations

5019:   Level: intermediate

5021:   Note:
5022:   This counter is reset to zero for each successive call to `TSSolve()`.

5024: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`
5025: @*/
5026: PetscErrorCode TSGetKSPIterations(TS ts, PetscInt *lits)
5027: {
5028:   PetscFunctionBegin;
5030:   PetscAssertPointer(lits, 2);
5031:   *lits = ts->ksp_its;
5032:   PetscFunctionReturn(PETSC_SUCCESS);
5033: }

5035: /*@
5036:   TSGetStepRejections - Gets the total number of rejected steps.

5038:   Not Collective

5040:   Input Parameter:
5041: . ts - `TS` context

5043:   Output Parameter:
5044: . rejects - number of steps rejected

5046:   Level: intermediate

5048:   Note:
5049:   This counter is reset to zero for each successive call to `TSSolve()`.

5051: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetSNESFailures()`, `TSSetMaxSNESFailures()`, `TSSetErrorIfStepFails()`
5052: @*/
5053: PetscErrorCode TSGetStepRejections(TS ts, PetscInt *rejects)
5054: {
5055:   PetscFunctionBegin;
5057:   PetscAssertPointer(rejects, 2);
5058:   *rejects = ts->reject;
5059:   PetscFunctionReturn(PETSC_SUCCESS);
5060: }

5062: /*@
5063:   TSGetSNESFailures - Gets the total number of failed `SNES` solves in a `TS`

5065:   Not Collective

5067:   Input Parameter:
5068: . ts - `TS` context

5070:   Output Parameter:
5071: . fails - number of failed nonlinear solves

5073:   Level: intermediate

5075:   Note:
5076:   This counter is reset to zero for each successive call to `TSSolve()`.

5078: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSSetMaxSNESFailures()`
5079: @*/
5080: PetscErrorCode TSGetSNESFailures(TS ts, PetscInt *fails)
5081: {
5082:   PetscFunctionBegin;
5084:   PetscAssertPointer(fails, 2);
5085:   *fails = ts->num_snes_failures;
5086:   PetscFunctionReturn(PETSC_SUCCESS);
5087: }

5089: /*@
5090:   TSSetMaxStepRejections - Sets the maximum number of step rejections allowed in a single time-step attempt before a time step fails in `TSSolve()` with `TS_DIVERGED_STEP_REJECTED`

5092:   Not Collective

5094:   Input Parameters:
5095: + ts      - `TS` context
5096: - rejects - maximum number of rejected steps, pass `PETSC_UNLIMITED` for unlimited

5098:   Options Database Key:
5099: . -ts_max_step_rejections - Maximum number of step rejections before a step fails

5101:   Level: intermediate

5103:   Developer Note:
5104:   The options database name is incorrect.

5106: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxSNESFailures()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSSetErrorIfStepFails()`,
5107:           `TSGetConvergedReason()`, `TSSolve()`, `TS_DIVERGED_STEP_REJECTED`
5108: @*/
5109: PetscErrorCode TSSetMaxStepRejections(TS ts, PetscInt rejects)
5110: {
5111:   PetscFunctionBegin;
5113:   if (rejects == PETSC_UNLIMITED || rejects == -1) {
5114:     ts->max_reject = PETSC_UNLIMITED;
5115:   } else {
5116:     PetscCheck(rejects >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of rejections");
5117:     ts->max_reject = rejects;
5118:   }
5119:   PetscFunctionReturn(PETSC_SUCCESS);
5120: }

5122: /*@
5123:   TSSetMaxSNESFailures - Sets the maximum number of failed `SNES` solves allowed before `TSSolve()` is ended with a `TSConvergedReason` of `TS_DIVERGED_NONLINEAR_SOLVE`

5125:   Not Collective

5127:   Input Parameters:
5128: + ts    - `TS` context
5129: - fails - maximum number of failed nonlinear solves, pass `PETSC_UNLIMITED` to allow any number of failures.

5131:   Options Database Key:
5132: . -ts_max_snes_failures - Maximum number of nonlinear solve failures

5134:   Level: intermediate

5136: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `SNESGetConvergedReason()`,
5137:           `TSGetConvergedReason()`, `TS_DIVERGED_NONLINEAR_SOLVE`, `TSConvergedReason`
5138: @*/
5139: PetscErrorCode TSSetMaxSNESFailures(TS ts, PetscInt fails)
5140: {
5141:   PetscFunctionBegin;
5143:   if (fails == PETSC_UNLIMITED || fails == -1) {
5144:     ts->max_snes_failures = PETSC_UNLIMITED;
5145:   } else {
5146:     PetscCheck(fails >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of failures");
5147:     ts->max_snes_failures = fails;
5148:   }
5149:   PetscFunctionReturn(PETSC_SUCCESS);
5150: }

5152: /*@
5153:   TSSetErrorIfStepFails - Immediately error if no step succeeds during `TSSolve()`

5155:   Not Collective

5157:   Input Parameters:
5158: + ts  - `TS` context
5159: - err - `PETSC_TRUE` to error if no step succeeds, `PETSC_FALSE` to return without failure

5161:   Options Database Key:
5162: . -ts_error_if_step_fails - Error if no step succeeds

5164:   Level: intermediate

5166: .seealso: [](ch_ts), `TS`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSGetConvergedReason()`
5167: @*/
5168: PetscErrorCode TSSetErrorIfStepFails(TS ts, PetscBool err)
5169: {
5170:   PetscFunctionBegin;
5172:   ts->errorifstepfailed = err;
5173:   PetscFunctionReturn(PETSC_SUCCESS);
5174: }

5176: /*@
5177:   TSGetAdapt - Get the adaptive controller context for the current method

5179:   Collective if controller has not yet been created

5181:   Input Parameter:
5182: . ts - time stepping context

5184:   Output Parameter:
5185: . adapt - adaptive controller

5187:   Level: intermediate

5189: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSAdaptSetType()`, `TSAdaptChoose()`
5190: @*/
5191: PetscErrorCode TSGetAdapt(TS ts, TSAdapt *adapt)
5192: {
5193:   PetscFunctionBegin;
5195:   PetscAssertPointer(adapt, 2);
5196:   if (!ts->adapt) {
5197:     PetscCall(TSAdaptCreate(PetscObjectComm((PetscObject)ts), &ts->adapt));
5198:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->adapt, (PetscObject)ts, 1));
5199:   }
5200:   *adapt = ts->adapt;
5201:   PetscFunctionReturn(PETSC_SUCCESS);
5202: }

5204: /*@
5205:   TSSetTolerances - Set tolerances for local truncation error when using an adaptive controller

5207:   Logically Collective

5209:   Input Parameters:
5210: + ts    - time integration context
5211: . atol  - scalar absolute tolerances
5212: . vatol - vector of absolute tolerances or `NULL`, used in preference to `atol` if present
5213: . rtol  - scalar relative tolerances
5214: - vrtol - vector of relative tolerances or `NULL`, used in preference to `rtol` if present

5216:   Options Database Keys:
5217: + -ts_rtol rtol - relative tolerance for local truncation error
5218: - -ts_atol atol - Absolute tolerance for local truncation error

5220:   Level: beginner

5222:   Notes:
5223:   `PETSC_CURRENT` or `PETSC_DETERMINE` may be used for `atol` or `rtol` to indicate the current value
5224:   or the default value from when the object's type was set.

5226:   With PETSc's implicit schemes for DAE problems, the calculation of the local truncation error
5227:   (LTE) includes both the differential and the algebraic variables. If one wants the LTE to be
5228:   computed only for the differential or the algebraic part then this can be done using the vector of
5229:   tolerances vatol. For example, by setting the tolerance vector with the desired tolerance for the
5230:   differential part and infinity for the algebraic part, the LTE calculation will include only the
5231:   differential variables.

5233:   Fortran Note:
5234:   Use `PETSC_CURRENT_INTEGER` or `PETSC_DETERMINE_INTEGER`.

5236: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSGetTolerances()`
5237: @*/
5238: PetscErrorCode TSSetTolerances(TS ts, PetscReal atol, Vec vatol, PetscReal rtol, Vec vrtol)
5239: {
5240:   PetscFunctionBegin;
5241:   if (atol == (PetscReal)PETSC_DETERMINE) {
5242:     ts->atol = ts->default_atol;
5243:   } else if (atol != (PetscReal)PETSC_CURRENT) {
5244:     PetscCheck(atol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Absolute tolerance %g must be non-negative", (double)atol);
5245:     ts->atol = atol;
5246:   }

5248:   if (vatol) {
5249:     PetscCall(PetscObjectReference((PetscObject)vatol));
5250:     PetscCall(VecDestroy(&ts->vatol));
5251:     ts->vatol = vatol;
5252:   }

5254:   if (rtol == (PetscReal)PETSC_DETERMINE) {
5255:     ts->rtol = ts->default_rtol;
5256:   } else if (rtol != (PetscReal)PETSC_CURRENT) {
5257:     PetscCheck(rtol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Relative tolerance %g must be non-negative", (double)rtol);
5258:     ts->rtol = rtol;
5259:   }

5261:   if (vrtol) {
5262:     PetscCall(PetscObjectReference((PetscObject)vrtol));
5263:     PetscCall(VecDestroy(&ts->vrtol));
5264:     ts->vrtol = vrtol;
5265:   }
5266:   PetscFunctionReturn(PETSC_SUCCESS);
5267: }

5269: /*@
5270:   TSGetTolerances - Get tolerances for local truncation error when using adaptive controller

5272:   Logically Collective

5274:   Input Parameter:
5275: . ts - time integration context

5277:   Output Parameters:
5278: + atol  - scalar absolute tolerances, `NULL` to ignore
5279: . vatol - vector of absolute tolerances, `NULL` to ignore
5280: . rtol  - scalar relative tolerances, `NULL` to ignore
5281: - vrtol - vector of relative tolerances, `NULL` to ignore

5283:   Level: beginner

5285: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSSetTolerances()`
5286: @*/
5287: PetscErrorCode TSGetTolerances(TS ts, PetscReal *atol, Vec *vatol, PetscReal *rtol, Vec *vrtol)
5288: {
5289:   PetscFunctionBegin;
5290:   if (atol) *atol = ts->atol;
5291:   if (vatol) *vatol = ts->vatol;
5292:   if (rtol) *rtol = ts->rtol;
5293:   if (vrtol) *vrtol = ts->vrtol;
5294:   PetscFunctionReturn(PETSC_SUCCESS);
5295: }

5297: /*@
5298:   TSErrorWeightedNorm - compute a weighted norm of the difference between two state vectors based on supplied absolute and relative tolerances

5300:   Collective

5302:   Input Parameters:
5303: + ts        - time stepping context
5304: . U         - state vector, usually ts->vec_sol
5305: . Y         - state vector to be compared to U
5306: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5308:   Output Parameters:
5309: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5310: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5311: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5313:   Options Database Key:
5314: . -ts_adapt_wnormtype wnormtype - 2, INFINITY

5316:   Level: developer

5318: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedENorm()`
5319: @*/
5320: PetscErrorCode TSErrorWeightedNorm(TS ts, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5321: {
5322:   PetscInt norma_loc, norm_loc, normr_loc;

5324:   PetscFunctionBegin;
5329:   PetscAssertPointer(norm, 5);
5330:   PetscAssertPointer(norma, 6);
5331:   PetscAssertPointer(normr, 7);
5332:   PetscCall(VecErrorWeightedNorms(U, Y, NULL, wnormtype, ts->atol, ts->vatol, ts->rtol, ts->vrtol, ts->adapt->ignore_max, norm, &norm_loc, norma, &norma_loc, normr, &normr_loc));
5333:   if (wnormtype == NORM_2) {
5334:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5335:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5336:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5337:   }
5338:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5339:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5340:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5341:   PetscFunctionReturn(PETSC_SUCCESS);
5342: }

5344: /*@
5345:   TSErrorWeightedENorm - compute a weighted error norm based on supplied absolute and relative tolerances

5347:   Collective

5349:   Input Parameters:
5350: + ts        - time stepping context
5351: . E         - error vector
5352: . U         - state vector, usually ts->vec_sol
5353: . Y         - state vector, previous time step
5354: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5356:   Output Parameters:
5357: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5358: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5359: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5361:   Options Database Key:
5362: . -ts_adapt_wnormtype wnormtype - 2, INFINITY

5364:   Level: developer

5366: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedNorm()`
5367: @*/
5368: PetscErrorCode TSErrorWeightedENorm(TS ts, Vec E, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5369: {
5370:   PetscInt norma_loc, norm_loc, normr_loc;

5372:   PetscFunctionBegin;
5374:   PetscCall(VecErrorWeightedNorms(U, Y, E, wnormtype, ts->atol, ts->vatol, ts->rtol, ts->vrtol, ts->adapt->ignore_max, norm, &norm_loc, norma, &norma_loc, normr, &normr_loc));
5375:   if (wnormtype == NORM_2) {
5376:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5377:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5378:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5379:   }
5380:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5381:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5382:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5383:   PetscFunctionReturn(PETSC_SUCCESS);
5384: }

5386: /*@
5387:   TSSetCFLTimeLocal - Set the local CFL constraint relative to forward Euler

5389:   Logically Collective

5391:   Input Parameters:
5392: + ts      - time stepping context
5393: - cfltime - maximum stable time step if using forward Euler (value can be different on each process)

5395:   Note:
5396:   After calling this function, the global CFL time can be obtained by calling TSGetCFLTime()

5398:   Level: intermediate

5400: .seealso: [](ch_ts), `TSGetCFLTime()`, `TSADAPTCFL`
5401: @*/
5402: PetscErrorCode TSSetCFLTimeLocal(TS ts, PetscReal cfltime)
5403: {
5404:   PetscFunctionBegin;
5406:   ts->cfltime_local = cfltime;
5407:   ts->cfltime       = -1.;
5408:   PetscFunctionReturn(PETSC_SUCCESS);
5409: }

5411: /*@
5412:   TSGetCFLTime - Get the maximum stable time step according to CFL criteria applied to forward Euler

5414:   Collective

5416:   Input Parameter:
5417: . ts - time stepping context

5419:   Output Parameter:
5420: . cfltime - maximum stable time step for forward Euler

5422:   Level: advanced

5424: .seealso: [](ch_ts), `TSSetCFLTimeLocal()`
5425: @*/
5426: PetscErrorCode TSGetCFLTime(TS ts, PetscReal *cfltime)
5427: {
5428:   PetscFunctionBegin;
5429:   if (ts->cfltime < 0) PetscCallMPI(MPIU_Allreduce(&ts->cfltime_local, &ts->cfltime, 1, MPIU_REAL, MPIU_MIN, PetscObjectComm((PetscObject)ts)));
5430:   *cfltime = ts->cfltime;
5431:   PetscFunctionReturn(PETSC_SUCCESS);
5432: }

5434: /*@
5435:   TSVISetVariableBounds - Sets the lower and upper bounds for the solution vector. xl <= x <= xu

5437:   Input Parameters:
5438: + ts - the `TS` context.
5439: . xl - lower bound.
5440: - xu - upper bound.

5442:   Level: advanced

5444:   Note:
5445:   If this routine is not called then the lower and upper bounds are set to
5446:   `PETSC_NINFINITY` and `PETSC_INFINITY` respectively during `SNESSetUp()`.

5448: .seealso: [](ch_ts), `TS`
5449: @*/
5450: PetscErrorCode TSVISetVariableBounds(TS ts, Vec xl, Vec xu)
5451: {
5452:   SNES snes;

5454:   PetscFunctionBegin;
5455:   PetscCall(TSGetSNES(ts, &snes));
5456:   PetscCall(SNESVISetVariableBounds(snes, xl, xu));
5457:   PetscFunctionReturn(PETSC_SUCCESS);
5458: }

5460: /*@
5461:   TSComputeLinearStability - computes the linear stability function at a point

5463:   Collective

5465:   Input Parameters:
5466: + ts - the `TS` context
5467: . xr - real part of input argument
5468: - xi - imaginary part of input argument

5470:   Output Parameters:
5471: + yr - real part of function value
5472: - yi - imaginary part of function value

5474:   Level: developer

5476: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSComputeIFunction()`
5477: @*/
5478: PetscErrorCode TSComputeLinearStability(TS ts, PetscReal xr, PetscReal xi, PetscReal *yr, PetscReal *yi)
5479: {
5480:   PetscFunctionBegin;
5482:   PetscUseTypeMethod(ts, linearstability, xr, xi, yr, yi);
5483:   PetscFunctionReturn(PETSC_SUCCESS);
5484: }

5486: /*@
5487:   TSRestartStep - Flags the solver to restart the next step

5489:   Collective

5491:   Input Parameter:
5492: . ts - the `TS` context obtained from `TSCreate()`

5494:   Level: advanced

5496:   Notes:
5497:   Multistep methods like `TSBDF` or Runge-Kutta methods with FSAL property require restarting the solver in the event of
5498:   discontinuities. These discontinuities may be introduced as a consequence of explicitly modifications to the solution
5499:   vector (which PETSc attempts to detect and handle) or problem coefficients (which PETSc is not able to detect). For
5500:   the sake of correctness and maximum safety, users are expected to call `TSRestart()` whenever they introduce
5501:   discontinuities in callback routines (e.g. prestep and poststep routines, or implicit/rhs function routines with
5502:   discontinuous source terms).

5504: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSSolve()`, `TSSetPreStep()`, `TSSetPostStep()`
5505: @*/
5506: PetscErrorCode TSRestartStep(TS ts)
5507: {
5508:   PetscFunctionBegin;
5510:   ts->steprestart = PETSC_TRUE;
5511:   PetscFunctionReturn(PETSC_SUCCESS);
5512: }

5514: /*@
5515:   TSRollBack - Rolls back one time step

5517:   Collective

5519:   Input Parameter:
5520: . ts - the `TS` context obtained from `TSCreate()`

5522:   Level: advanced

5524: .seealso: [](ch_ts), `TS`, `TSGetStepRollBack()`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSInterpolate()`
5525: @*/
5526: PetscErrorCode TSRollBack(TS ts)
5527: {
5528:   PetscFunctionBegin;
5530:   PetscCheck(!ts->steprollback, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "TSRollBack already called");
5531:   PetscTryTypeMethod(ts, rollback);
5532:   PetscCall(VecCopy(ts->vec_sol0, ts->vec_sol));
5533:   ts->time_step  = ts->ptime - ts->ptime_prev;
5534:   ts->ptime      = ts->ptime_prev;
5535:   ts->ptime_prev = ts->ptime_prev_rollback;
5536:   ts->steps--;
5537:   ts->steprollback = PETSC_TRUE;
5538:   PetscFunctionReturn(PETSC_SUCCESS);
5539: }

5541: /*@
5542:   TSGetStepRollBack - Get the internal flag indicating if you are rolling back a step

5544:   Not collective

5546:   Input Parameter:
5547: . ts - the `TS` context obtained from `TSCreate()`

5549:   Output Parameter:
5550: . flg - the rollback flag

5552:   Level: advanced

5554: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSRollBack()`
5555: @*/
5556: PetscErrorCode TSGetStepRollBack(TS ts, PetscBool *flg)
5557: {
5558:   PetscFunctionBegin;
5560:   PetscAssertPointer(flg, 2);
5561:   *flg = ts->steprollback;
5562:   PetscFunctionReturn(PETSC_SUCCESS);
5563: }

5565: /*@
5566:   TSGetStepResize - Get the internal flag indicating if the current step is after a resize.

5568:   Not collective

5570:   Input Parameter:
5571: . ts - the `TS` context obtained from `TSCreate()`

5573:   Output Parameter:
5574: . flg - the resize flag

5576:   Level: advanced

5578: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetResize()`
5579: @*/
5580: PetscErrorCode TSGetStepResize(TS ts, PetscBool *flg)
5581: {
5582:   PetscFunctionBegin;
5584:   PetscAssertPointer(flg, 2);
5585:   *flg = ts->stepresize;
5586:   PetscFunctionReturn(PETSC_SUCCESS);
5587: }

5589: /*@
5590:   TSGetStages - Get the number of stages and stage values

5592:   Input Parameter:
5593: . ts - the `TS` context obtained from `TSCreate()`

5595:   Output Parameters:
5596: + ns - the number of stages
5597: - Y  - the current stage vectors

5599:   Level: advanced

5601:   Note:
5602:   Both `ns` and `Y` can be `NULL`.

5604: .seealso: [](ch_ts), `TS`, `TSCreate()`
5605: @*/
5606: PetscErrorCode TSGetStages(TS ts, PetscInt *ns, Vec **Y)
5607: {
5608:   PetscFunctionBegin;
5610:   if (ns) PetscAssertPointer(ns, 2);
5611:   if (Y) PetscAssertPointer(Y, 3);
5612:   if (!ts->ops->getstages) {
5613:     if (ns) *ns = 0;
5614:     if (Y) *Y = NULL;
5615:   } else PetscUseTypeMethod(ts, getstages, ns, Y);
5616:   PetscFunctionReturn(PETSC_SUCCESS);
5617: }

5619: /*@
5620:   TSComputeIJacobianDefaultColor - Computes the Jacobian using finite differences and coloring to exploit matrix sparsity.

5622:   Collective

5624:   Input Parameters:
5625: + ts    - the `TS` context
5626: . t     - current timestep
5627: . U     - state vector
5628: . Udot  - time derivative of state vector
5629: . shift - shift to apply, see note below
5630: - ctx   - an optional application context

5632:   Output Parameters:
5633: + J - Jacobian matrix (not altered in this routine)
5634: - B - newly computed Jacobian matrix to use with preconditioner (generally the same as `J`)

5636:   Level: intermediate

5638:   Notes:
5639:   If F(t,U,Udot)=0 is the DAE, the required Jacobian is

5641:   dF/dU + shift*dF/dUdot

5643:   Most users should not need to explicitly call this routine, as it
5644:   is used internally within the nonlinear solvers.

5646:   This will first try to get the coloring from the `DM`.  If the `DM` type has no coloring
5647:   routine, then it will try to get the coloring from the matrix.  This requires that the
5648:   matrix have nonzero entries precomputed.

5650: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
5651: @*/
5652: PetscErrorCode TSComputeIJacobianDefaultColor(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat J, Mat B, PetscCtx ctx)
5653: {
5654:   SNES          snes;
5655:   MatFDColoring color;
5656:   PetscBool     hascolor, matcolor = PETSC_FALSE;

5658:   PetscFunctionBegin;
5659:   PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_fd_color_use_mat", &matcolor, NULL));
5660:   PetscCall(PetscObjectQuery((PetscObject)B, "TSMatFDColoring", (PetscObject *)&color));
5661:   if (!color) {
5662:     DM         dm;
5663:     ISColoring iscoloring;

5665:     PetscCall(TSGetDM(ts, &dm));
5666:     PetscCall(DMHasColoring(dm, &hascolor));
5667:     if (hascolor && !matcolor) {
5668:       PetscCall(DMCreateColoring(dm, IS_COLORING_GLOBAL, &iscoloring));
5669:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5670:       PetscCall(MatFDColoringSetFunction(color, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
5671:       PetscCall(MatFDColoringSetFromOptions(color));
5672:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5673:       PetscCall(ISColoringDestroy(&iscoloring));
5674:     } else {
5675:       MatColoring mc;

5677:       PetscCall(MatColoringCreate(B, &mc));
5678:       PetscCall(MatColoringSetDistance(mc, 2));
5679:       PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
5680:       PetscCall(MatColoringSetFromOptions(mc));
5681:       PetscCall(MatColoringApply(mc, &iscoloring));
5682:       PetscCall(MatColoringDestroy(&mc));
5683:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5684:       PetscCall(MatFDColoringSetFunction(color, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
5685:       PetscCall(MatFDColoringSetFromOptions(color));
5686:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5687:       PetscCall(ISColoringDestroy(&iscoloring));
5688:     }
5689:     PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)color));
5690:     PetscCall(PetscObjectDereference((PetscObject)color));
5691:   }
5692:   PetscCall(TSGetSNES(ts, &snes));
5693:   PetscCall(MatFDColoringApply(B, color, U, snes));
5694:   if (J != B) {
5695:     PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
5696:     PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));
5697:   }
5698:   PetscFunctionReturn(PETSC_SUCCESS);
5699: }

5701: /*@
5702:   TSSetFunctionDomainError - Set a function that tests if the current state vector is valid

5704:   Logically collective

5706:   Input Parameters:
5707: + ts   - the `TS` context
5708: - func - function called within `TSFunctionDomainError()`

5710:   Calling sequence of `func`:
5711: + ts     - the `TS` context
5712: . time   - the current time (of the stage)
5713: . state  - the state to check if it is valid
5714: - accept - (output parameter) `PETSC_FALSE` if the state is not acceptable, `PETSC_TRUE` if acceptable

5716:   Level: intermediate

5718:   Notes:
5719:   `accept` must be collectively specified.
5720:   If an implicit ODE solver is being used then, in addition to providing this routine, the
5721:   user's code should call `SNESSetFunctionDomainError()` when domain errors occur during
5722:   function evaluations where the functions are provided by `TSSetIFunction()` or `TSSetRHSFunction()`.
5723:   Use `TSGetSNES()` to obtain the `SNES` object

5725:   Developer Notes:
5726:   The naming of this function is inconsistent with the `SNESSetFunctionDomainError()`
5727:   since one takes a function pointer and the other does not.

5729: .seealso: [](ch_ts), `TSAdaptCheckStage()`, `TSFunctionDomainError()`, `SNESSetFunctionDomainError()`, `TSGetSNES()`
5730: @*/
5731: PetscErrorCode TSSetFunctionDomainError(TS ts, PetscErrorCode (*func)(TS ts, PetscReal time, Vec state, PetscBool *accept))
5732: {
5733:   PetscFunctionBegin;
5735:   ts->functiondomainerror = func;
5736:   PetscFunctionReturn(PETSC_SUCCESS);
5737: }

5739: /*@
5740:   TSFunctionDomainError - Checks if the current state is valid

5742:   Collective

5744:   Input Parameters:
5745: + ts        - the `TS` context
5746: . stagetime - time of the simulation
5747: - Y         - state vector to check.

5749:   Output Parameter:
5750: . accept - Set to `PETSC_FALSE` if the current state vector is valid.

5752:   Level: developer

5754:   Note:
5755:   This function is called by the `TS` integration routines and calls the user provided function (set with `TSSetFunctionDomainError()`)
5756:   to check if the current state is valid.

5758: .seealso: [](ch_ts), `TS`, `TSSetFunctionDomainError()`
5759: @*/
5760: PetscErrorCode TSFunctionDomainError(TS ts, PetscReal stagetime, Vec Y, PetscBool *accept)
5761: {
5762:   PetscFunctionBegin;
5766:   PetscAssertPointer(accept, 4);
5767:   *accept = PETSC_TRUE;
5768:   if (ts->functiondomainerror) PetscCall((*ts->functiondomainerror)(ts, stagetime, Y, accept));
5769:   PetscFunctionReturn(PETSC_SUCCESS);
5770: }

5772: /*@
5773:   TSClone - This function clones a time step `TS` object.

5775:   Collective

5777:   Input Parameter:
5778: . tsin - The input `TS`

5780:   Output Parameter:
5781: . tsout - The output `TS` (cloned)

5783:   Level: developer

5785:   Notes:
5786:   This function is used to create a clone of a `TS` object. It is used in `TSARKIMEX` for initializing the slope for first stage explicit methods.
5787:   It will likely be replaced in the future with a mechanism of switching methods on the fly.

5789:   When using `TSDestroy()` on a clone the user has to first reset the correct `TS` reference in the embedded `SNES` object: e.g., by running
5790: .vb
5791:  SNES snes_dup = NULL;
5792:  TSGetSNES(ts,&snes_dup);
5793:  TSSetSNES(ts,snes_dup);
5794: .ve

5796: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetType()`, `TSSetUp()`, `TSDestroy()`, `TSSetProblemType()`
5797: @*/
5798: PetscErrorCode TSClone(TS tsin, TS *tsout)
5799: {
5800:   TS     t;
5801:   SNES   snes_start;
5802:   DM     dm;
5803:   TSType type;

5805:   PetscFunctionBegin;
5806:   PetscAssertPointer(tsin, 1);
5807:   *tsout = NULL;

5809:   PetscCall(PetscHeaderCreate(t, TS_CLASSID, "TS", "Time stepping", "TS", PetscObjectComm((PetscObject)tsin), TSDestroy, TSView));

5811:   /* General TS description */
5812:   t->numbermonitors    = 0;
5813:   t->setupcalled       = PETSC_FALSE;
5814:   t->ksp_its           = 0;
5815:   t->snes_its          = 0;
5816:   t->nwork             = 0;
5817:   t->rhsjacobian.time  = PETSC_MIN_REAL;
5818:   t->rhsjacobian.scale = 1.;
5819:   t->ijacobian.shift   = 1.;

5821:   PetscCall(TSGetSNES(tsin, &snes_start));
5822:   PetscCall(TSSetSNES(t, snes_start));

5824:   PetscCall(TSGetDM(tsin, &dm));
5825:   PetscCall(TSSetDM(t, dm));

5827:   t->adapt = tsin->adapt;
5828:   PetscCall(PetscObjectReference((PetscObject)t->adapt));

5830:   t->trajectory = tsin->trajectory;
5831:   PetscCall(PetscObjectReference((PetscObject)t->trajectory));

5833:   t->event = tsin->event;
5834:   if (t->event) t->event->refct++;

5836:   t->problem_type      = tsin->problem_type;
5837:   t->ptime             = tsin->ptime;
5838:   t->ptime_prev        = tsin->ptime_prev;
5839:   t->time_step         = tsin->time_step;
5840:   t->max_time          = tsin->max_time;
5841:   t->steps             = tsin->steps;
5842:   t->max_steps         = tsin->max_steps;
5843:   t->equation_type     = tsin->equation_type;
5844:   t->atol              = tsin->atol;
5845:   t->rtol              = tsin->rtol;
5846:   t->max_snes_failures = tsin->max_snes_failures;
5847:   t->max_reject        = tsin->max_reject;
5848:   t->errorifstepfailed = tsin->errorifstepfailed;

5850:   PetscCall(TSGetType(tsin, &type));
5851:   PetscCall(TSSetType(t, type));

5853:   t->vec_sol = NULL;

5855:   t->cfltime          = tsin->cfltime;
5856:   t->cfltime_local    = tsin->cfltime_local;
5857:   t->exact_final_time = tsin->exact_final_time;

5859:   t->ops[0] = tsin->ops[0];

5861:   if (((PetscObject)tsin)->fortran_func_pointers) {
5862:     PetscCall(PetscMalloc((10) * sizeof(PetscFortranCallbackFn *), &((PetscObject)t)->fortran_func_pointers));
5863:     for (PetscInt i = 0; i < 10; i++) ((PetscObject)t)->fortran_func_pointers[i] = ((PetscObject)tsin)->fortran_func_pointers[i];
5864:   }
5865:   *tsout = t;
5866:   PetscFunctionReturn(PETSC_SUCCESS);
5867: }

5869: static PetscErrorCode RHSWrapperFunction_TSRHSJacobianTest(PetscCtx ctx, Vec x, Vec y)
5870: {
5871:   TS ts = (TS)ctx;

5873:   PetscFunctionBegin;
5874:   PetscCall(TSComputeRHSFunction(ts, 0, x, y));
5875:   PetscFunctionReturn(PETSC_SUCCESS);
5876: }

5878: /*@
5879:   TSRHSJacobianTest - Compares the multiply routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5881:   Logically Collective

5883:   Input Parameter:
5884: . ts - the time stepping routine

5886:   Output Parameter:
5887: . flg - `PETSC_TRUE` if the multiply is likely correct

5889:   Options Database Key:
5890: . -ts_rhs_jacobian_test_mult -mat_shell_test_mult_view - run the test at each timestep of the integrator

5892:   Level: advanced

5894:   Note:
5895:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5897: .seealso: [](ch_ts), `TS`, `Mat`, `MATSHELL`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTestTranspose()`
5898: @*/
5899: PetscErrorCode TSRHSJacobianTest(TS ts, PetscBool *flg)
5900: {
5901:   Mat              J, B;
5902:   TSRHSJacobianFn *func;
5903:   void            *ctx;

5905:   PetscFunctionBegin;
5906:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5907:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5908:   PetscCall(MatShellTestMult(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5909:   PetscFunctionReturn(PETSC_SUCCESS);
5910: }

5912: /*@
5913:   TSRHSJacobianTestTranspose - Compares the multiply transpose routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5915:   Logically Collective

5917:   Input Parameter:
5918: . ts - the time stepping routine

5920:   Output Parameter:
5921: . flg - `PETSC_TRUE` if the multiply is likely correct

5923:   Options Database Key:
5924: . -ts_rhs_jacobian_test_mult_transpose -mat_shell_test_mult_transpose_view - run the test at each timestep of the integrator

5926:   Level: advanced

5928:   Notes:
5929:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5931: .seealso: [](ch_ts), `TS`, `Mat`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTest()`
5932: @*/
5933: PetscErrorCode TSRHSJacobianTestTranspose(TS ts, PetscBool *flg)
5934: {
5935:   Mat              J, B;
5936:   void            *ctx;
5937:   TSRHSJacobianFn *func;

5939:   PetscFunctionBegin;
5940:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5941:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5942:   PetscCall(MatShellTestMultTranspose(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5943:   PetscFunctionReturn(PETSC_SUCCESS);
5944: }

5946: /*@
5947:   TSSetUseSplitRHSFunction - Use the split RHSFunction when a multirate method is used.

5949:   Logically Collective

5951:   Input Parameters:
5952: + ts                   - timestepping context
5953: - use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5955:   Options Database Key:
5956: . -ts_use_splitrhsfunction (true|false) - use the split RHS function for multirate solvers

5958:   Level: intermediate

5960:   Note:
5961:   This is only for multirate methods

5963: .seealso: [](ch_ts), `TS`, `TSGetUseSplitRHSFunction()`
5964: @*/
5965: PetscErrorCode TSSetUseSplitRHSFunction(TS ts, PetscBool use_splitrhsfunction)
5966: {
5967:   PetscFunctionBegin;
5969:   ts->use_splitrhsfunction = use_splitrhsfunction;
5970:   PetscFunctionReturn(PETSC_SUCCESS);
5971: }

5973: /*@
5974:   TSGetUseSplitRHSFunction - Gets whether to use the split RHSFunction when a multirate method is used.

5976:   Not Collective

5978:   Input Parameter:
5979: . ts - timestepping context

5981:   Output Parameter:
5982: . use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5984:   Level: intermediate

5986: .seealso: [](ch_ts), `TS`, `TSSetUseSplitRHSFunction()`
5987: @*/
5988: PetscErrorCode TSGetUseSplitRHSFunction(TS ts, PetscBool *use_splitrhsfunction)
5989: {
5990:   PetscFunctionBegin;
5992:   *use_splitrhsfunction = ts->use_splitrhsfunction;
5993:   PetscFunctionReturn(PETSC_SUCCESS);
5994: }

5996: /*@
5997:   TSSetMatStructure - sets the relationship between the nonzero structure of the RHS Jacobian matrix to the IJacobian matrix.

5999:   Logically  Collective

6001:   Input Parameters:
6002: + ts  - the time-stepper
6003: - str - the structure (the default is `UNKNOWN_NONZERO_PATTERN`)

6005:   Level: intermediate

6007:   Note:
6008:   When the relationship between the nonzero structures is known and supplied the solution process can be much faster

6010: .seealso: [](ch_ts), `TS`, `MatAXPY()`, `MatStructure`
6011:  @*/
6012: PetscErrorCode TSSetMatStructure(TS ts, MatStructure str)
6013: {
6014:   PetscFunctionBegin;
6016:   ts->axpy_pattern = str;
6017:   PetscFunctionReturn(PETSC_SUCCESS);
6018: }

6020: /*@
6021:   TSSetEvaluationTimes - sets the evaluation points. The solution will be computed and stored for each time requested

6023:   Collective

6025:   Input Parameters:
6026: + ts          - the time-stepper
6027: . n           - number of the time points
6028: - time_points - array of the time points, must be increasing

6030:   Options Database Key:
6031: . -ts_eval_times t0,...,tn - Sets the evaluation times

6033:   Level: intermediate

6035:   Notes:
6036:   The elements in `time_points` must be all increasing. They correspond to the intermediate points to be saved.

6038:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

6040:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using evaluation times may
6041:   pressure the memory system when using a large number of time points.

6043: .seealso: [](ch_ts), `TS`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`, `TSSetTimeSpan()`
6044:  @*/
6045: PetscErrorCode TSSetEvaluationTimes(TS ts, PetscInt n, PetscReal time_points[])
6046: {
6047:   PetscBool is_sorted;

6049:   PetscFunctionBegin;
6051:   if (ts->eval_times) { // Reset eval_times
6052:     ts->eval_times->sol_idx        = 0;
6053:     ts->eval_times->time_point_idx = 0;
6054:     if (n != ts->eval_times->num_time_points) {
6055:       PetscCall(PetscFree(ts->eval_times->time_points));
6056:       PetscCall(PetscFree(ts->eval_times->sol_times));
6057:       PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
6058:     } else {
6059:       PetscCall(PetscArrayzero(ts->eval_times->sol_times, n));
6060:       for (PetscInt i = 0; i < n; i++) PetscCall(VecZeroEntries(ts->eval_times->sol_vecs[i]));
6061:     }
6062:   } else { // Create/initialize eval_times
6063:     TSEvaluationTimes eval_times;
6064:     PetscCall(PetscNew(&eval_times));
6065:     PetscCall(PetscMalloc1(n, &eval_times->time_points));
6066:     PetscCall(PetscMalloc1(n, &eval_times->sol_times));
6067:     eval_times->reltol  = 1e-6;
6068:     eval_times->abstol  = 10 * PETSC_MACHINE_EPSILON;
6069:     eval_times->worktol = 0;
6070:     ts->eval_times      = eval_times;
6071:   }
6072:   ts->eval_times->num_time_points = n;
6073:   PetscCall(PetscSortedReal(n, time_points, &is_sorted));
6074:   PetscCheck(is_sorted, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "time_points array must be sorted");
6075:   PetscCall(PetscArraycpy(ts->eval_times->time_points, time_points, n));
6076:   // Note: ts->vec_sol not guaranteed to exist, so ts->eval_times->sol_vecs allocated at TSSolve time
6077:   PetscFunctionReturn(PETSC_SUCCESS);
6078: }

6080: /*@
6081:   TSGetEvaluationTimes - gets the evaluation times set with `TSSetEvaluationTimes()`

6083:   Not Collective

6085:   Input Parameter:
6086: . ts - the time-stepper

6088:   Output Parameters:
6089: + n           - number of the time points
6090: - time_points - array of the time points

6092:   Level: beginner

6094:   Note:
6095:   The values obtained are valid until the `TS` object is destroyed.

6097:   Both `n` and `time_points` can be `NULL`.

6099:   Also used to see time points set by `TSSetTimeSpan()`.

6101: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationSolutions()`
6102:  @*/
6103: PetscErrorCode TSGetEvaluationTimes(TS ts, PetscInt *n, const PetscReal *time_points[])
6104: {
6105:   PetscFunctionBegin;
6107:   if (n) PetscAssertPointer(n, 2);
6108:   if (time_points) PetscAssertPointer(time_points, 3);
6109:   if (!ts->eval_times) {
6110:     if (n) *n = 0;
6111:     if (time_points) *time_points = NULL;
6112:   } else {
6113:     if (n) *n = ts->eval_times->num_time_points;
6114:     if (time_points) *time_points = ts->eval_times->time_points;
6115:   }
6116:   PetscFunctionReturn(PETSC_SUCCESS);
6117: }

6119: /*@
6120:   TSGetEvaluationSolutions - Get the number of solutions and the solutions at the evaluation time points specified

6122:   Input Parameter:
6123: . ts - the `TS` context obtained from `TSCreate()`

6125:   Output Parameters:
6126: + nsol      - the number of solutions
6127: . sol_times - array of solution times corresponding to the solution vectors. See note below
6128: - Sols      - the solution vectors

6130:   Level: intermediate

6132:   Notes:
6133:   Both `nsol` and `Sols` can be `NULL`.

6135:   Some time points in the evaluation points may be skipped by `TS` so that `nsol` is less than the number of points specified by `TSSetEvaluationTimes()`.
6136:   For example, manipulating the step size, especially with a reduced precision, may cause `TS` to step over certain evaluation times.

6138:   Also used to see view solutions requested by `TSSetTimeSpan()`.

6140: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`
6141: @*/
6142: PetscErrorCode TSGetEvaluationSolutions(TS ts, PetscInt *nsol, const PetscReal *sol_times[], Vec *Sols[])
6143: {
6144:   PetscFunctionBegin;
6146:   if (nsol) PetscAssertPointer(nsol, 2);
6147:   if (sol_times) PetscAssertPointer(sol_times, 3);
6148:   if (Sols) PetscAssertPointer(Sols, 4);
6149:   if (!ts->eval_times) {
6150:     if (nsol) *nsol = 0;
6151:     if (sol_times) *sol_times = NULL;
6152:     if (Sols) *Sols = NULL;
6153:   } else {
6154:     if (nsol) *nsol = ts->eval_times->sol_idx;
6155:     if (sol_times) *sol_times = ts->eval_times->sol_times;
6156:     if (Sols) *Sols = ts->eval_times->sol_vecs;
6157:   }
6158:   PetscFunctionReturn(PETSC_SUCCESS);
6159: }

6161: /*@
6162:   TSSetTimeSpan - sets the time span. The solution will be computed and stored for each time requested in the span

6164:   Collective

6166:   Input Parameters:
6167: + ts         - the time-stepper
6168: . n          - number of the time points (>=2)
6169: - span_times - array of the time points, must be increasing. The first element and the last element are the initial time and the final time respectively.

6171:   Options Database Key:
6172: . -ts_time_span t0,...,tf - Sets the time span

6174:   Level: intermediate

6176:   Notes:
6177:   This function is identical to `TSSetEvaluationTimes()`, except that it also sets the initial time and final time for the `ts` to the first and last `span_times` entries.

6179:   The elements in `span_times` must be all increasing. They correspond to the intermediate points to be saved.

6181:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

6183:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using time span may
6184:   pressure the memory system when using a large number of span points.

6186: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`
6187:  @*/
6188: PetscErrorCode TSSetTimeSpan(TS ts, PetscInt n, PetscReal span_times[])
6189: {
6190:   PetscFunctionBegin;
6192:   PetscCheck(n >= 2, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Minimum time span size is 2 but %" PetscInt_FMT " is provided", n);
6193:   PetscCall(TSSetEvaluationTimes(ts, n, span_times));
6194:   PetscCall(TSSetTime(ts, span_times[0]));
6195:   PetscCall(TSSetMaxTime(ts, span_times[n - 1]));
6196:   PetscFunctionReturn(PETSC_SUCCESS);
6197: }

6199: /*@
6200:   TSPruneIJacobianColor - Remove nondiagonal zeros in the Jacobian matrix and update the `MatMFFD` coloring information.

6202:   Collective

6204:   Input Parameters:
6205: + ts - the `TS` context
6206: . J  - Jacobian matrix (not altered in this routine)
6207: - B  - newly computed Jacobian matrix to use with preconditioner

6209:   Level: intermediate

6211:   Notes:
6212:   This function improves the `MatFDColoring` performance when the Jacobian matrix was over-allocated or contains
6213:   many constant zeros entries, which is typically the case when the matrix is generated by a `DM`
6214:   and multiple fields are involved.

6216:   Users need to make sure that the Jacobian matrix is properly filled to reflect the sparsity
6217:   structure. For `MatFDColoring`, the values of nonzero entries are not important. So one can
6218:   usually call `TSComputeIJacobian()` with randomized input vectors to generate a dummy Jacobian.
6219:   `TSComputeIJacobian()` should be called before `TSSolve()` but after `TSSetUp()`.

6221: .seealso: [](ch_ts), `TS`, `MatFDColoring`, `TSComputeIJacobianDefaultColor()`, `MatEliminateZeros()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
6222: @*/
6223: PetscErrorCode TSPruneIJacobianColor(TS ts, Mat J, Mat B)
6224: {
6225:   MatColoring   mc            = NULL;
6226:   ISColoring    iscoloring    = NULL;
6227:   MatFDColoring matfdcoloring = NULL;

6229:   PetscFunctionBegin;
6230:   /* Generate new coloring after eliminating zeros in the matrix */
6231:   PetscCall(MatEliminateZeros(B, PETSC_TRUE));
6232:   PetscCall(MatColoringCreate(B, &mc));
6233:   PetscCall(MatColoringSetDistance(mc, 2));
6234:   PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
6235:   PetscCall(MatColoringSetFromOptions(mc));
6236:   PetscCall(MatColoringApply(mc, &iscoloring));
6237:   PetscCall(MatColoringDestroy(&mc));
6238:   /* Replace the old coloring with the new one */
6239:   PetscCall(MatFDColoringCreate(B, iscoloring, &matfdcoloring));
6240:   PetscCall(MatFDColoringSetFunction(matfdcoloring, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
6241:   PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
6242:   PetscCall(MatFDColoringSetUp(B, iscoloring, matfdcoloring));
6243:   PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)matfdcoloring));
6244:   PetscCall(PetscObjectDereference((PetscObject)matfdcoloring));
6245:   PetscCall(ISColoringDestroy(&iscoloring));
6246:   PetscFunctionReturn(PETSC_SUCCESS);
6247: }