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>                                                    - EULER, BEULER, SUNDIALS, PSEUDO, CN, RK, THETA, ALPHA, GLLE,  SSP, GLEE, BSYMP, IRK, 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 <yes,no>                                         - 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, 256, &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 defined(PETSC_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, void *))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 type - 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`, `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:   if (ts->trajectory) 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 - Evaluates the Jacobian of the DAE

865:   Collective

867:   Input Parameters:
868: + ts    - the `TS` context
869: . t     - current timestep
870: . U     - state vector
871: . Udot  - time derivative of state vector
872: . shift - shift to apply, see note below
873: - imex  - flag indicates if the method is `TSARKIMEX` so that the RHSJacobian should be kept separate

875:   Output Parameters:
876: + A - Jacobian matrix
877: - B - matrix from which the preconditioner is constructed; often the same as `A`

879:   Level: developer

881:   Notes:
882:   If $ F(t,U,\dot{U})=0 $ is the DAE, the required Jacobian is
883: .vb
884:    dF/dU + shift*dF/dUdot
885: .ve
886:   Most users should not need to explicitly call this routine, as it
887:   is used internally within the nonlinear solvers.

889: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`
890: @*/
891: PetscErrorCode TSComputeIJacobian(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, PetscBool imex)
892: {
893:   TSIJacobianFn   *ijacobian;
894:   TSRHSJacobianFn *rhsjacobian;
895:   DM               dm;
896:   void            *ctx;

898:   PetscFunctionBegin;

905:   PetscCall(TSGetDM(ts, &dm));
906:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, &ctx));
907:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));

909:   PetscCheck(rhsjacobian || ijacobian, PetscObjectComm((PetscObject)ts), PETSC_ERR_USER, "Must call TSSetRHSJacobian() and / or TSSetIJacobian()");

911:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, A, B));
912:   if (ijacobian) {
913:     PetscCallBack("TS callback implicit Jacobian", (*ijacobian)(ts, t, U, Udot, shift, A, B, ctx));
914:     ts->ijacs++;
915:   }
916:   if (imex) {
917:     if (!ijacobian) { /* system was written as Udot = G(t,U) */
918:       PetscBool assembled;
919:       if (rhsjacobian) {
920:         Mat Arhs = NULL;
921:         PetscCall(TSGetRHSMats_Private(ts, &Arhs, NULL));
922:         if (A == Arhs) {
923:           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 */
924:           ts->rhsjacobian.time = PETSC_MIN_REAL;
925:         }
926:       }
927:       PetscCall(MatZeroEntries(A));
928:       PetscCall(MatAssembled(A, &assembled));
929:       if (!assembled) {
930:         PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
931:         PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
932:       }
933:       PetscCall(MatShift(A, shift));
934:       if (A != B) {
935:         PetscCall(MatZeroEntries(B));
936:         PetscCall(MatAssembled(B, &assembled));
937:         if (!assembled) {
938:           PetscCall(MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY));
939:           PetscCall(MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY));
940:         }
941:         PetscCall(MatShift(B, shift));
942:       }
943:     }
944:   } else {
945:     Mat Arhs = NULL, Brhs = NULL;

947:     /* RHSJacobian needs to be converted to part of IJacobian if exists */
948:     if (rhsjacobian) PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
949:     if (Arhs == A) { /* No IJacobian matrix, so we only have the RHS matrix */
950:       PetscObjectState Ustate;
951:       PetscObjectId    Uid;
952:       TSRHSFunctionFn *rhsfunction;

954:       PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));
955:       PetscCall(PetscObjectStateGet((PetscObject)U, &Ustate));
956:       PetscCall(PetscObjectGetId((PetscObject)U, &Uid));
957:       if ((rhsjacobian == TSComputeRHSJacobianConstant || (ts->rhsjacobian.time == t && (ts->problem_type == TS_LINEAR || (ts->rhsjacobian.Xid == Uid && ts->rhsjacobian.Xstate == Ustate)) && rhsfunction != TSComputeRHSFunctionLinear)) &&
958:           ts->rhsjacobian.scale == -1.) {                      /* No need to recompute RHSJacobian */
959:         PetscCall(MatShift(A, shift - ts->rhsjacobian.shift)); /* revert the old shift and add the new shift with a single call to MatShift */
960:         if (A != B) PetscCall(MatShift(B, shift - ts->rhsjacobian.shift));
961:       } else {
962:         PetscBool flg;

964:         if (ts->rhsjacobian.reuse) { /* Undo the damage */
965:           /* MatScale has a short path for this case.
966:              However, this code path is taken the first time TSComputeRHSJacobian is called
967:              and the matrices have not been assembled yet */
968:           PetscCall(TSRecoverRHSJacobian(ts, A, B));
969:         }
970:         PetscCall(TSComputeRHSJacobian(ts, t, U, A, B));
971:         PetscCall(SNESGetUseMatrixFree(ts->snes, NULL, &flg));
972:         /* since -snes_mf_operator uses the full SNES function it does not need to be shifted or scaled here */
973:         if (!flg) {
974:           PetscCall(MatScale(A, -1));
975:           PetscCall(MatShift(A, shift));
976:         }
977:         if (A != B) {
978:           PetscCall(MatScale(B, -1));
979:           PetscCall(MatShift(B, shift));
980:         }
981:       }
982:       ts->rhsjacobian.scale = -1;
983:       ts->rhsjacobian.shift = shift;
984:     } else if (Arhs) {  /* Both IJacobian and RHSJacobian */
985:       if (!ijacobian) { /* No IJacobian provided, but we have a separate RHS matrix */
986:         PetscCall(MatZeroEntries(A));
987:         PetscCall(MatShift(A, shift));
988:         if (A != B) {
989:           PetscCall(MatZeroEntries(B));
990:           PetscCall(MatShift(B, shift));
991:         }
992:       }
993:       PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
994:       PetscCall(MatAXPY(A, -1, Arhs, ts->axpy_pattern));
995:       if (A != B) PetscCall(MatAXPY(B, -1, Brhs, ts->axpy_pattern));
996:     }
997:   }
998:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, A, B));
999:   PetscFunctionReturn(PETSC_SUCCESS);
1000: }

1002: /*@C
1003:   TSSetRHSFunction - Sets the routine for evaluating the function,
1004:   where U_t = G(t,u).

1006:   Logically Collective

1008:   Input Parameters:
1009: + ts  - the `TS` context obtained from `TSCreate()`
1010: . r   - vector to put the computed right-hand side (or `NULL` to have it created)
1011: . f   - routine for evaluating the right-hand-side function
1012: - ctx - [optional] user-defined context for private data for the function evaluation routine (may be `NULL`)

1014:   Level: beginner

1016:   Note:
1017:   You must call this function or `TSSetIFunction()` to define your ODE. You cannot use this function when solving a DAE.

1019: .seealso: [](ch_ts), `TS`, `TSRHSFunctionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSSetIFunction()`
1020: @*/
1021: PetscErrorCode TSSetRHSFunction(TS ts, Vec r, TSRHSFunctionFn *f, void *ctx)
1022: {
1023:   SNES snes;
1024:   Vec  ralloc = NULL;
1025:   DM   dm;

1027:   PetscFunctionBegin;

1031:   PetscCall(TSGetDM(ts, &dm));
1032:   PetscCall(DMTSSetRHSFunction(dm, f, ctx));
1033:   PetscCall(TSGetSNES(ts, &snes));
1034:   if (!r && !ts->dm && ts->vec_sol) {
1035:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1036:     r = ralloc;
1037:   }
1038:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1039:   PetscCall(VecDestroy(&ralloc));
1040:   PetscFunctionReturn(PETSC_SUCCESS);
1041: }

1043: /*@C
1044:   TSSetSolutionFunction - Provide a function that computes the solution of the ODE or DAE

1046:   Logically Collective

1048:   Input Parameters:
1049: + ts  - the `TS` context obtained from `TSCreate()`
1050: . f   - routine for evaluating the solution
1051: - ctx - [optional] user-defined context for private data for the
1052:           function evaluation routine (may be `NULL`)

1054:   Options Database Keys:
1055: + -ts_monitor_lg_error   - create a graphical monitor of error history, requires user to have provided `TSSetSolutionFunction()`
1056: - -ts_monitor_draw_error - Monitor error graphically, requires user to have provided `TSSetSolutionFunction()`

1058:   Level: intermediate

1060:   Notes:
1061:   This routine is used for testing accuracy of time integration schemes when you already know the solution.
1062:   If analytic solutions are not known for your system, consider using the Method of Manufactured Solutions to
1063:   create closed-form solutions with non-physical forcing terms.

1065:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1067: .seealso: [](ch_ts), `TS`, `TSSolutionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSComputeSolutionFunction()`, `TSSetForcingFunction()`, `TSSetSolution()`, `TSGetSolution()`, `TSMonitorLGError()`, `TSMonitorDrawError()`
1068: @*/
1069: PetscErrorCode TSSetSolutionFunction(TS ts, TSSolutionFn *f, void *ctx)
1070: {
1071:   DM dm;

1073:   PetscFunctionBegin;
1075:   PetscCall(TSGetDM(ts, &dm));
1076:   PetscCall(DMTSSetSolutionFunction(dm, f, ctx));
1077:   PetscFunctionReturn(PETSC_SUCCESS);
1078: }

1080: /*@C
1081:   TSSetForcingFunction - Provide a function that computes a forcing term for a ODE or PDE

1083:   Logically Collective

1085:   Input Parameters:
1086: + ts   - the `TS` context obtained from `TSCreate()`
1087: . func - routine for evaluating the forcing function
1088: - ctx  - [optional] user-defined context for private data for the function evaluation routine
1089:          (may be `NULL`)

1091:   Level: intermediate

1093:   Notes:
1094:   This routine is useful for testing accuracy of time integration schemes when using the Method of Manufactured Solutions to
1095:   create closed-form solutions with a non-physical forcing term. It allows you to use the Method of Manufactored Solution without directly editing the
1096:   definition of the problem you are solving and hence possibly introducing bugs.

1098:   This replaces the ODE F(u,u_t,t) = 0 the `TS` is solving with F(u,u_t,t) - func(t) = 0

1100:   This forcing function does not depend on the solution to the equations, it can only depend on spatial location, time, and possibly parameters, the
1101:   parameters can be passed in the ctx variable.

1103:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1105: .seealso: [](ch_ts), `TS`, `TSForcingFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`,
1106: `TSComputeSolutionFunction()`, `TSSetSolutionFunction()`
1107: @*/
1108: PetscErrorCode TSSetForcingFunction(TS ts, TSForcingFn *func, void *ctx)
1109: {
1110:   DM dm;

1112:   PetscFunctionBegin;
1114:   PetscCall(TSGetDM(ts, &dm));
1115:   PetscCall(DMTSSetForcingFunction(dm, func, ctx));
1116:   PetscFunctionReturn(PETSC_SUCCESS);
1117: }

1119: /*@C
1120:   TSSetRHSJacobian - Sets the function to compute the Jacobian of G,
1121:   where U_t = G(U,t), as well as the location to store the matrix.

1123:   Logically Collective

1125:   Input Parameters:
1126: + ts   - the `TS` context obtained from `TSCreate()`
1127: . Amat - (approximate) location to store Jacobian matrix entries computed by `f`
1128: . Pmat - matrix from which preconditioner is to be constructed (usually the same as `Amat`)
1129: . f    - the Jacobian evaluation routine
1130: - ctx  - [optional] user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1132:   Level: beginner

1134:   Notes:
1135:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1137:   The `TS` solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f()`
1138:   You should not assume the values are the same in the next call to f() as you set them in the previous call.

1140: .seealso: [](ch_ts), `TS`, `TSRHSJacobianFn`, `SNESComputeJacobianDefaultColor()`,
1141: `TSSetRHSFunction()`, `TSRHSJacobianSetReuse()`, `TSSetIJacobian()`, `TSRHSFunctionFn`, `TSIFunctionFn`
1142: @*/
1143: PetscErrorCode TSSetRHSJacobian(TS ts, Mat Amat, Mat Pmat, TSRHSJacobianFn *f, void *ctx)
1144: {
1145:   SNES           snes;
1146:   DM             dm;
1147:   TSIJacobianFn *ijacobian;

1149:   PetscFunctionBegin;
1153:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1154:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1156:   PetscCall(TSGetDM(ts, &dm));
1157:   PetscCall(DMTSSetRHSJacobian(dm, f, ctx));
1158:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, NULL));
1159:   PetscCall(TSGetSNES(ts, &snes));
1160:   if (!ijacobian) PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1161:   if (Amat) {
1162:     PetscCall(PetscObjectReference((PetscObject)Amat));
1163:     PetscCall(MatDestroy(&ts->Arhs));
1164:     ts->Arhs = Amat;
1165:   }
1166:   if (Pmat) {
1167:     PetscCall(PetscObjectReference((PetscObject)Pmat));
1168:     PetscCall(MatDestroy(&ts->Brhs));
1169:     ts->Brhs = Pmat;
1170:   }
1171:   PetscFunctionReturn(PETSC_SUCCESS);
1172: }

1174: /*@C
1175:   TSSetIFunction - Set the function to compute F(t,U,U_t) where F() = 0 is the DAE to be solved.

1177:   Logically Collective

1179:   Input Parameters:
1180: + ts  - the `TS` context obtained from `TSCreate()`
1181: . r   - vector to hold the residual (or `NULL` to have it created internally)
1182: . f   - the function evaluation routine
1183: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1185:   Level: beginner

1187:   Note:
1188:   The user MUST call either this routine or `TSSetRHSFunction()` to define the ODE.  When solving DAEs you must use this function.

1190: .seealso: [](ch_ts), `TS`, `TSIFunctionFn`, `TSSetRHSJacobian()`, `TSSetRHSFunction()`,
1191: `TSSetIJacobian()`
1192: @*/
1193: PetscErrorCode TSSetIFunction(TS ts, Vec r, TSIFunctionFn *f, void *ctx)
1194: {
1195:   SNES snes;
1196:   Vec  ralloc = NULL;
1197:   DM   dm;

1199:   PetscFunctionBegin;

1203:   PetscCall(TSGetDM(ts, &dm));
1204:   PetscCall(DMTSSetIFunction(dm, f, ctx));

1206:   PetscCall(TSGetSNES(ts, &snes));
1207:   if (!r && !ts->dm && ts->vec_sol) {
1208:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1209:     r = ralloc;
1210:   }
1211:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1212:   PetscCall(VecDestroy(&ralloc));
1213:   PetscFunctionReturn(PETSC_SUCCESS);
1214: }

1216: /*@C
1217:   TSGetIFunction - Returns the vector where the implicit residual is stored and the function/context to compute it.

1219:   Not Collective

1221:   Input Parameter:
1222: . ts - the `TS` context

1224:   Output Parameters:
1225: + r    - vector to hold residual (or `NULL`)
1226: . func - the function to compute residual (or `NULL`)
1227: - ctx  - the function context (or `NULL`)

1229:   Level: advanced

1231: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`
1232: @*/
1233: PetscErrorCode TSGetIFunction(TS ts, Vec *r, TSIFunctionFn **func, void **ctx)
1234: {
1235:   SNES snes;
1236:   DM   dm;

1238:   PetscFunctionBegin;
1240:   PetscCall(TSGetSNES(ts, &snes));
1241:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1242:   PetscCall(TSGetDM(ts, &dm));
1243:   PetscCall(DMTSGetIFunction(dm, func, ctx));
1244:   PetscFunctionReturn(PETSC_SUCCESS);
1245: }

1247: /*@C
1248:   TSGetRHSFunction - Returns the vector where the right-hand side is stored and the function/context to compute it.

1250:   Not Collective

1252:   Input Parameter:
1253: . ts - the `TS` context

1255:   Output Parameters:
1256: + r    - vector to hold computed right-hand side (or `NULL`)
1257: . func - the function to compute right-hand side (or `NULL`)
1258: - ctx  - the function context (or `NULL`)

1260:   Level: advanced

1262: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `SNESGetFunction()`
1263: @*/
1264: PetscErrorCode TSGetRHSFunction(TS ts, Vec *r, TSRHSFunctionFn **func, void **ctx)
1265: {
1266:   SNES snes;
1267:   DM   dm;

1269:   PetscFunctionBegin;
1271:   PetscCall(TSGetSNES(ts, &snes));
1272:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1273:   PetscCall(TSGetDM(ts, &dm));
1274:   PetscCall(DMTSGetRHSFunction(dm, func, ctx));
1275:   PetscFunctionReturn(PETSC_SUCCESS);
1276: }

1278: /*@C
1279:   TSSetIJacobian - Set the function to compute the matrix dF/dU + a*dF/dU_t where F(t,U,U_t) is the function
1280:   provided with `TSSetIFunction()`.

1282:   Logically Collective

1284:   Input Parameters:
1285: + ts   - the `TS` context obtained from `TSCreate()`
1286: . Amat - (approximate) matrix to store Jacobian entries computed by `f`
1287: . Pmat - matrix used to compute preconditioner (usually the same as `Amat`)
1288: . f    - the Jacobian evaluation routine
1289: - ctx  - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1291:   Level: beginner

1293:   Notes:
1294:   The matrices `Amat` and `Pmat` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1296:   If you know the operator Amat has a null space you can use `MatSetNullSpace()` and `MatSetTransposeNullSpace()` to supply the null
1297:   space to `Amat` and the `KSP` solvers will automatically use that null space as needed during the solution process.

1299:   The matrix dF/dU + a*dF/dU_t you provide turns out to be
1300:   the Jacobian of F(t,U,W+a*U) where F(t,U,U_t) = 0 is the DAE to be solved.
1301:   The time integrator internally approximates U_t by W+a*U where the positive "shift"
1302:   a and vector W depend on the integration method, step size, and past states. For example with
1303:   the backward Euler method a = 1/dt and W = -a*U(previous timestep) so
1304:   W + a*U = a*(U - U(previous timestep)) = (U - U(previous timestep))/dt

1306:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1308:   The TS solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f`
1309:   You should not assume the values are the same in the next call to `f` as you set them in the previous call.

1311:   In case `TSSetRHSJacobian()` is also used in conjunction with a fully-implicit solver,
1312:   multilevel linear solvers, e.g. `PCMG`, will likely not work due to the way `TS` handles rhs matrices.

1314: .seealso: [](ch_ts), `TS`, `TSIJacobianFn`, `TSSetIFunction()`, `TSSetRHSJacobian()`,
1315: `SNESComputeJacobianDefaultColor()`, `SNESComputeJacobianDefault()`, `TSSetRHSFunction()`
1316: @*/
1317: PetscErrorCode TSSetIJacobian(TS ts, Mat Amat, Mat Pmat, TSIJacobianFn *f, void *ctx)
1318: {
1319:   SNES snes;
1320:   DM   dm;

1322:   PetscFunctionBegin;
1326:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1327:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1329:   PetscCall(TSGetDM(ts, &dm));
1330:   PetscCall(DMTSSetIJacobian(dm, f, ctx));

1332:   PetscCall(TSGetSNES(ts, &snes));
1333:   PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1334:   PetscFunctionReturn(PETSC_SUCCESS);
1335: }

1337: /*@
1338:   TSRHSJacobianSetReuse - restore the RHS Jacobian before calling the user-provided `TSRHSJacobianFn` function again

1340:   Logically Collective

1342:   Input Parameters:
1343: + ts    - `TS` context obtained from `TSCreate()`
1344: - reuse - `PETSC_TRUE` if the RHS Jacobian

1346:   Level: intermediate

1348:   Notes:
1349:   Without this flag, `TS` will change the sign and shift the RHS Jacobian for a
1350:   finite-time-step implicit solve, in which case the user function will need to recompute the
1351:   entire Jacobian.  The `reuse `flag must be set if the evaluation function assumes that the
1352:   matrix entries have not been changed by the `TS`.

1354: .seealso: [](ch_ts), `TS`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
1355: @*/
1356: PetscErrorCode TSRHSJacobianSetReuse(TS ts, PetscBool reuse)
1357: {
1358:   PetscFunctionBegin;
1359:   ts->rhsjacobian.reuse = reuse;
1360:   PetscFunctionReturn(PETSC_SUCCESS);
1361: }

1363: /*@C
1364:   TSSetI2Function - Set the function to compute F(t,U,U_t,U_tt) where F = 0 is the DAE to be solved.

1366:   Logically Collective

1368:   Input Parameters:
1369: + ts  - the `TS` context obtained from `TSCreate()`
1370: . F   - vector to hold the residual (or `NULL` to have it created internally)
1371: . fun - the function evaluation routine
1372: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1374:   Level: beginner

1376: .seealso: [](ch_ts), `TS`, `TSI2FunctionFn`, `TSSetI2Jacobian()`, `TSSetIFunction()`,
1377: `TSCreate()`, `TSSetRHSFunction()`
1378: @*/
1379: PetscErrorCode TSSetI2Function(TS ts, Vec F, TSI2FunctionFn *fun, void *ctx)
1380: {
1381:   DM dm;

1383:   PetscFunctionBegin;
1386:   PetscCall(TSSetIFunction(ts, F, NULL, NULL));
1387:   PetscCall(TSGetDM(ts, &dm));
1388:   PetscCall(DMTSSetI2Function(dm, fun, ctx));
1389:   PetscFunctionReturn(PETSC_SUCCESS);
1390: }

1392: /*@C
1393:   TSGetI2Function - Returns the vector where the implicit residual is stored and the function/context to compute it.

1395:   Not Collective

1397:   Input Parameter:
1398: . ts - the `TS` context

1400:   Output Parameters:
1401: + r   - vector to hold residual (or `NULL`)
1402: . fun - the function to compute residual (or `NULL`)
1403: - ctx - the function context (or `NULL`)

1405:   Level: advanced

1407: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`, `TSCreate()`
1408: @*/
1409: PetscErrorCode TSGetI2Function(TS ts, Vec *r, TSI2FunctionFn **fun, void **ctx)
1410: {
1411:   SNES snes;
1412:   DM   dm;

1414:   PetscFunctionBegin;
1416:   PetscCall(TSGetSNES(ts, &snes));
1417:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1418:   PetscCall(TSGetDM(ts, &dm));
1419:   PetscCall(DMTSGetI2Function(dm, fun, ctx));
1420:   PetscFunctionReturn(PETSC_SUCCESS);
1421: }

1423: /*@C
1424:   TSSetI2Jacobian - Set the function to compute the matrix dF/dU + v*dF/dU_t  + a*dF/dU_tt
1425:   where F(t,U,U_t,U_tt) is the function you provided with `TSSetI2Function()`.

1427:   Logically Collective

1429:   Input Parameters:
1430: + ts  - the `TS` context obtained from `TSCreate()`
1431: . J   - matrix to hold the Jacobian values
1432: . P   - matrix for constructing the preconditioner (may be same as `J`)
1433: . jac - the Jacobian evaluation routine, see `TSI2JacobianFn` for the calling sequence
1434: - ctx - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1436:   Level: beginner

1438:   Notes:
1439:   The matrices `J` and `P` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1441:   The matrix dF/dU + v*dF/dU_t + a*dF/dU_tt you provide turns out to be
1442:   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.
1443:   The time integrator internally approximates U_t by W+v*U and U_tt by W'+a*U  where the positive "shift"
1444:   parameters 'v' and 'a' and vectors W, W' depend on the integration method, step size, and past states.

1446: .seealso: [](ch_ts), `TS`, `TSI2JacobianFn`, `TSSetI2Function()`, `TSGetI2Jacobian()`
1447: @*/
1448: PetscErrorCode TSSetI2Jacobian(TS ts, Mat J, Mat P, TSI2JacobianFn *jac, void *ctx)
1449: {
1450:   DM dm;

1452:   PetscFunctionBegin;
1456:   PetscCall(TSSetIJacobian(ts, J, P, NULL, NULL));
1457:   PetscCall(TSGetDM(ts, &dm));
1458:   PetscCall(DMTSSetI2Jacobian(dm, jac, ctx));
1459:   PetscFunctionReturn(PETSC_SUCCESS);
1460: }

1462: /*@C
1463:   TSGetI2Jacobian - Returns the implicit Jacobian at the present timestep.

1465:   Not Collective, but parallel objects are returned if `TS` is parallel

1467:   Input Parameter:
1468: . ts - The `TS` context obtained from `TSCreate()`

1470:   Output Parameters:
1471: + J   - The (approximate) Jacobian of F(t,U,U_t,U_tt)
1472: . P   - The matrix from which the preconditioner is constructed, often the same as `J`
1473: . jac - The function to compute the Jacobian matrices
1474: - ctx - User-defined context for Jacobian evaluation routine

1476:   Level: advanced

1478:   Note:
1479:   You can pass in `NULL` for any return argument you do not need.

1481: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`, `TSSetI2Jacobian()`, `TSGetI2Function()`, `TSCreate()`
1482: @*/
1483: PetscErrorCode TSGetI2Jacobian(TS ts, Mat *J, Mat *P, TSI2JacobianFn **jac, void **ctx)
1484: {
1485:   SNES snes;
1486:   DM   dm;

1488:   PetscFunctionBegin;
1489:   PetscCall(TSGetSNES(ts, &snes));
1490:   PetscCall(SNESSetUpMatrices(snes));
1491:   PetscCall(SNESGetJacobian(snes, J, P, NULL, NULL));
1492:   PetscCall(TSGetDM(ts, &dm));
1493:   PetscCall(DMTSGetI2Jacobian(dm, jac, ctx));
1494:   PetscFunctionReturn(PETSC_SUCCESS);
1495: }

1497: /*@
1498:   TSComputeI2Function - Evaluates the DAE residual written in implicit form F(t,U,U_t,U_tt) = 0

1500:   Collective

1502:   Input Parameters:
1503: + ts - the `TS` context
1504: . t  - current time
1505: . U  - state vector
1506: . V  - time derivative of state vector (U_t)
1507: - A  - second time derivative of state vector (U_tt)

1509:   Output Parameter:
1510: . F - the residual vector

1512:   Level: developer

1514:   Note:
1515:   Most users should not need to explicitly call this routine, as it
1516:   is used internally within the nonlinear solvers.

1518: .seealso: [](ch_ts), `TS`, `TSSetI2Function()`, `TSGetI2Function()`
1519: @*/
1520: PetscErrorCode TSComputeI2Function(TS ts, PetscReal t, Vec U, Vec V, Vec A, Vec F)
1521: {
1522:   DM               dm;
1523:   TSI2FunctionFn  *I2Function;
1524:   void            *ctx;
1525:   TSRHSFunctionFn *rhsfunction;

1527:   PetscFunctionBegin;

1534:   PetscCall(TSGetDM(ts, &dm));
1535:   PetscCall(DMTSGetI2Function(dm, &I2Function, &ctx));
1536:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));

1538:   if (!I2Function) {
1539:     PetscCall(TSComputeIFunction(ts, t, U, A, F, PETSC_FALSE));
1540:     PetscFunctionReturn(PETSC_SUCCESS);
1541:   }

1543:   PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, V, F));

1545:   PetscCallBack("TS callback implicit function", I2Function(ts, t, U, V, A, F, ctx));

1547:   if (rhsfunction) {
1548:     Vec Frhs;

1550:     PetscCall(DMGetGlobalVector(dm, &Frhs));
1551:     PetscCall(TSComputeRHSFunction(ts, t, U, Frhs));
1552:     PetscCall(VecAXPY(F, -1, Frhs));
1553:     PetscCall(DMRestoreGlobalVector(dm, &Frhs));
1554:   }

1556:   PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, V, F));
1557:   PetscFunctionReturn(PETSC_SUCCESS);
1558: }

1560: /*@
1561:   TSComputeI2Jacobian - Evaluates the Jacobian of the DAE

1563:   Collective

1565:   Input Parameters:
1566: + ts     - the `TS` context
1567: . t      - current timestep
1568: . U      - state vector
1569: . V      - time derivative of state vector
1570: . A      - second time derivative of state vector
1571: . shiftV - shift to apply, see note below
1572: - shiftA - shift to apply, see note below

1574:   Output Parameters:
1575: + J - Jacobian matrix
1576: - P - optional matrix used to construct the preconditioner

1578:   Level: developer

1580:   Notes:
1581:   If $F(t,U,V,A) = 0$ is the DAE, the required Jacobian is

1583: $$
1584:   dF/dU + shiftV*dF/dV + shiftA*dF/dA
1585: $$

1587:   Most users should not need to explicitly call this routine, as it
1588:   is used internally within the ODE integrators.

1590: .seealso: [](ch_ts), `TS`, `TSSetI2Jacobian()`
1591: @*/
1592: PetscErrorCode TSComputeI2Jacobian(TS ts, PetscReal t, Vec U, Vec V, Vec A, PetscReal shiftV, PetscReal shiftA, Mat J, Mat P)
1593: {
1594:   DM               dm;
1595:   TSI2JacobianFn  *I2Jacobian;
1596:   void            *ctx;
1597:   TSRHSJacobianFn *rhsjacobian;

1599:   PetscFunctionBegin;

1607:   PetscCall(TSGetDM(ts, &dm));
1608:   PetscCall(DMTSGetI2Jacobian(dm, &I2Jacobian, &ctx));
1609:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));

1611:   if (!I2Jacobian) {
1612:     PetscCall(TSComputeIJacobian(ts, t, U, A, shiftA, J, P, PETSC_FALSE));
1613:     PetscFunctionReturn(PETSC_SUCCESS);
1614:   }

1616:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, J, P));
1617:   PetscCallBack("TS callback implicit Jacobian", I2Jacobian(ts, t, U, V, A, shiftV, shiftA, J, P, ctx));
1618:   if (rhsjacobian) {
1619:     Mat Jrhs, Prhs;
1620:     PetscCall(TSGetRHSMats_Private(ts, &Jrhs, &Prhs));
1621:     PetscCall(TSComputeRHSJacobian(ts, t, U, Jrhs, Prhs));
1622:     PetscCall(MatAXPY(J, -1, Jrhs, ts->axpy_pattern));
1623:     if (P != J) PetscCall(MatAXPY(P, -1, Prhs, ts->axpy_pattern));
1624:   }

1626:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, J, P));
1627:   PetscFunctionReturn(PETSC_SUCCESS);
1628: }

1630: /*@C
1631:   TSSetTransientVariable - sets function to transform from state to transient variables

1633:   Logically Collective

1635:   Input Parameters:
1636: + ts   - time stepping context on which to change the transient variable
1637: . tvar - a function that transforms to transient variables, see `TSTransientVariableFn` for the calling sequence
1638: - ctx  - a context for tvar

1640:   Level: advanced

1642:   Notes:
1643:   This is typically used to transform from primitive to conservative variables so that a time integrator (e.g., `TSBDF`)
1644:   can be conservative.  In this context, primitive variables P are used to model the state (e.g., because they lead to
1645:   well-conditioned formulations even in limiting cases such as low-Mach or zero porosity).  The transient variable is
1646:   C(P), specified by calling this function.  An IFunction thus receives arguments (P, Cdot) and the IJacobian must be
1647:   evaluated via the chain rule, as in
1648: .vb
1649:      dF/dP + shift * dF/dCdot dC/dP.
1650: .ve

1652: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSTransientVariableFn`, `DMTSSetTransientVariable()`, `DMTSGetTransientVariable()`, `TSSetIFunction()`, `TSSetIJacobian()`
1653: @*/
1654: PetscErrorCode TSSetTransientVariable(TS ts, TSTransientVariableFn *tvar, void *ctx)
1655: {
1656:   DM dm;

1658:   PetscFunctionBegin;
1660:   PetscCall(TSGetDM(ts, &dm));
1661:   PetscCall(DMTSSetTransientVariable(dm, tvar, ctx));
1662:   PetscFunctionReturn(PETSC_SUCCESS);
1663: }

1665: /*@
1666:   TSComputeTransientVariable - transforms state (primitive) variables to transient (conservative) variables

1668:   Logically Collective

1670:   Input Parameters:
1671: + ts - TS on which to compute
1672: - U  - state vector to be transformed to transient variables

1674:   Output Parameter:
1675: . C - transient (conservative) variable

1677:   Level: developer

1679:   Developer Notes:
1680:   If `DMTSSetTransientVariable()` has not been called, then C is not modified in this routine and C = `NULL` is allowed.
1681:   This makes it safe to call without a guard.  One can use `TSHasTransientVariable()` to check if transient variables are
1682:   being used.

1684: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeIFunction()`, `TSComputeIJacobian()`
1685: @*/
1686: PetscErrorCode TSComputeTransientVariable(TS ts, Vec U, Vec C)
1687: {
1688:   DM   dm;
1689:   DMTS dmts;

1691:   PetscFunctionBegin;
1694:   PetscCall(TSGetDM(ts, &dm));
1695:   PetscCall(DMGetDMTS(dm, &dmts));
1696:   if (dmts->ops->transientvar) {
1698:     PetscCall((*dmts->ops->transientvar)(ts, U, C, dmts->transientvarctx));
1699:   }
1700:   PetscFunctionReturn(PETSC_SUCCESS);
1701: }

1703: /*@
1704:   TSHasTransientVariable - determine whether transient variables have been set

1706:   Logically Collective

1708:   Input Parameter:
1709: . ts - `TS` on which to compute

1711:   Output Parameter:
1712: . has - `PETSC_TRUE` if transient variables have been set

1714:   Level: developer

1716: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeTransientVariable()`
1717: @*/
1718: PetscErrorCode TSHasTransientVariable(TS ts, PetscBool *has)
1719: {
1720:   DM   dm;
1721:   DMTS dmts;

1723:   PetscFunctionBegin;
1725:   PetscCall(TSGetDM(ts, &dm));
1726:   PetscCall(DMGetDMTS(dm, &dmts));
1727:   *has = dmts->ops->transientvar ? PETSC_TRUE : PETSC_FALSE;
1728:   PetscFunctionReturn(PETSC_SUCCESS);
1729: }

1731: /*@
1732:   TS2SetSolution - Sets the initial solution and time derivative vectors
1733:   for use by the `TS` routines handling second order equations.

1735:   Logically Collective

1737:   Input Parameters:
1738: + ts - the `TS` context obtained from `TSCreate()`
1739: . u  - the solution vector
1740: - v  - the time derivative vector

1742:   Level: beginner

1744: .seealso: [](ch_ts), `TS`
1745: @*/
1746: PetscErrorCode TS2SetSolution(TS ts, Vec u, Vec v)
1747: {
1748:   PetscFunctionBegin;
1752:   PetscCall(TSSetSolution(ts, u));
1753:   PetscCall(PetscObjectReference((PetscObject)v));
1754:   PetscCall(VecDestroy(&ts->vec_dot));
1755:   ts->vec_dot = v;
1756:   PetscFunctionReturn(PETSC_SUCCESS);
1757: }

1759: /*@
1760:   TS2GetSolution - Returns the solution and time derivative at the present timestep
1761:   for second order equations.

1763:   Not Collective

1765:   Input Parameter:
1766: . ts - the `TS` context obtained from `TSCreate()`

1768:   Output Parameters:
1769: + u - the vector containing the solution
1770: - v - the vector containing the time derivative

1772:   Level: intermediate

1774:   Notes:
1775:   It is valid to call this routine inside the function
1776:   that you are evaluating in order to move to the new timestep. This vector not
1777:   changed until the solution at the next timestep has been calculated.

1779: .seealso: [](ch_ts), `TS`, `TS2SetSolution()`, `TSGetTimeStep()`, `TSGetTime()`
1780: @*/
1781: PetscErrorCode TS2GetSolution(TS ts, Vec *u, Vec *v)
1782: {
1783:   PetscFunctionBegin;
1785:   if (u) PetscAssertPointer(u, 2);
1786:   if (v) PetscAssertPointer(v, 3);
1787:   if (u) *u = ts->vec_sol;
1788:   if (v) *v = ts->vec_dot;
1789:   PetscFunctionReturn(PETSC_SUCCESS);
1790: }

1792: /*@
1793:   TSLoad - Loads a `TS` that has been stored in binary  with `TSView()`.

1795:   Collective

1797:   Input Parameters:
1798: + ts     - the newly loaded `TS`, this needs to have been created with `TSCreate()` or
1799:            some related function before a call to `TSLoad()`.
1800: - viewer - binary file viewer, obtained from `PetscViewerBinaryOpen()`

1802:   Level: intermediate

1804:   Note:
1805:   The type is determined by the data in the file, any type set into the `TS` before this call is ignored.

1807: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerBinaryOpen()`, `TSView()`, `MatLoad()`, `VecLoad()`
1808: @*/
1809: PetscErrorCode TSLoad(TS ts, PetscViewer viewer)
1810: {
1811:   PetscBool isbinary;
1812:   PetscInt  classid;
1813:   char      type[256];
1814:   DMTS      sdm;
1815:   DM        dm;

1817:   PetscFunctionBegin;
1820:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1821:   PetscCheck(isbinary, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid viewer; open viewer with PetscViewerBinaryOpen()");

1823:   PetscCall(PetscViewerBinaryRead(viewer, &classid, 1, NULL, PETSC_INT));
1824:   PetscCheck(classid == TS_FILE_CLASSID, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Not TS next in file");
1825:   PetscCall(PetscViewerBinaryRead(viewer, type, 256, NULL, PETSC_CHAR));
1826:   PetscCall(TSSetType(ts, type));
1827:   PetscTryTypeMethod(ts, load, viewer);
1828:   PetscCall(DMCreate(PetscObjectComm((PetscObject)ts), &dm));
1829:   PetscCall(DMLoad(dm, viewer));
1830:   PetscCall(TSSetDM(ts, dm));
1831:   PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
1832:   PetscCall(VecLoad(ts->vec_sol, viewer));
1833:   PetscCall(DMGetDMTS(ts->dm, &sdm));
1834:   PetscCall(DMTSLoad(sdm, viewer));
1835:   PetscFunctionReturn(PETSC_SUCCESS);
1836: }

1838: #include <petscdraw.h>
1839: #if defined(PETSC_HAVE_SAWS)
1840: #include <petscviewersaws.h>
1841: #endif

1843: /*@
1844:   TSViewFromOptions - View a `TS` based on values in the options database

1846:   Collective

1848:   Input Parameters:
1849: + ts   - the `TS` context
1850: . obj  - Optional object that provides the prefix for the options database keys
1851: - name - command line option string to be passed by user

1853:   Level: intermediate

1855: .seealso: [](ch_ts), `TS`, `TSView`, `PetscObjectViewFromOptions()`, `TSCreate()`
1856: @*/
1857: PetscErrorCode TSViewFromOptions(TS ts, PetscObject obj, const char name[])
1858: {
1859:   PetscFunctionBegin;
1861:   PetscCall(PetscObjectViewFromOptions((PetscObject)ts, obj, name));
1862:   PetscFunctionReturn(PETSC_SUCCESS);
1863: }

1865: /*@
1866:   TSView - Prints the `TS` data structure.

1868:   Collective

1870:   Input Parameters:
1871: + ts     - the `TS` context obtained from `TSCreate()`
1872: - viewer - visualization context

1874:   Options Database Key:
1875: . -ts_view - calls `TSView()` at end of `TSStep()`

1877:   Level: beginner

1879:   Notes:
1880:   The available visualization contexts include
1881: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
1882: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
1883:   output where only the first processor opens
1884:   the file.  All other processors send their
1885:   data to the first processor to print.

1887:   The user can open an alternative visualization context with
1888:   `PetscViewerASCIIOpen()` - output to a specified file.

1890:   In the debugger you can do call `TSView`(ts,0) to display the `TS` solver. (The same holds for any PETSc object viewer).

1892:   The "initial time step" displayed is the default time step from `TSCreate()` or that set with `TSSetTimeStep()` or `-ts_time_step`

1894: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerASCIIOpen()`
1895: @*/
1896: PetscErrorCode TSView(TS ts, PetscViewer viewer)
1897: {
1898:   TSType    type;
1899:   PetscBool isascii, isstring, issundials, isbinary, isdraw;
1900:   DMTS      sdm;
1901: #if defined(PETSC_HAVE_SAWS)
1902:   PetscBool issaws;
1903: #endif

1905:   PetscFunctionBegin;
1907:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ts), &viewer));
1909:   PetscCheckSameComm(ts, 1, viewer, 2);

1911:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
1912:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
1913:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1914:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
1915: #if defined(PETSC_HAVE_SAWS)
1916:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSAWS, &issaws));
1917: #endif
1918:   if (isascii) {
1919:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)ts, viewer));
1920:     if (ts->ops->view) {
1921:       PetscCall(PetscViewerASCIIPushTab(viewer));
1922:       PetscUseTypeMethod(ts, view, viewer);
1923:       PetscCall(PetscViewerASCIIPopTab(viewer));
1924:     }
1925:     PetscCall(PetscViewerASCIIPrintf(viewer, "  initial time step=%g\n", (double)ts->initial_time_step));
1926:     if (ts->max_steps < PETSC_INT_MAX) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum steps=%" PetscInt_FMT "\n", ts->max_steps));
1927:     if (ts->run_steps < PETSC_INT_MAX) PetscCall(PetscViewerASCIIPrintf(viewer, "  run steps=%" PetscInt_FMT "\n", ts->run_steps));
1928:     if (ts->max_time < PETSC_MAX_REAL) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum time=%g\n", (double)ts->max_time));
1929:     if (ts->max_reject != PETSC_UNLIMITED) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum number of step rejections=%" PetscInt_FMT "\n", ts->max_reject));
1930:     if (ts->max_snes_failures != PETSC_UNLIMITED) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum number of SNES failures allowed=%" PetscInt_FMT "\n", ts->max_snes_failures));
1931:     if (ts->ifuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I function evaluations=%" PetscInt_FMT "\n", ts->ifuncs));
1932:     if (ts->ijacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I Jacobian evaluations=%" PetscInt_FMT "\n", ts->ijacs));
1933:     if (ts->rhsfuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS function evaluations=%" PetscInt_FMT "\n", ts->rhsfuncs));
1934:     if (ts->rhsjacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS Jacobian evaluations=%" PetscInt_FMT "\n", ts->rhsjacs));
1935:     if (ts->usessnes) {
1936:       PetscBool lin;
1937:       if (ts->problem_type == TS_NONLINEAR) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of nonlinear solver iterations=%" PetscInt_FMT "\n", ts->snes_its));
1938:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of linear solver iterations=%" PetscInt_FMT "\n", ts->ksp_its));
1939:       PetscCall(PetscObjectTypeCompareAny((PetscObject)ts->snes, &lin, SNESKSPONLY, SNESKSPTRANSPOSEONLY, ""));
1940:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of %slinear solve failures=%" PetscInt_FMT "\n", lin ? "" : "non", ts->num_snes_failures));
1941:     }
1942:     PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of rejected steps=%" PetscInt_FMT "\n", ts->reject));
1943:     if (ts->vrtol) PetscCall(PetscViewerASCIIPrintf(viewer, "  using vector of relative error tolerances, "));
1944:     else PetscCall(PetscViewerASCIIPrintf(viewer, "  using relative error tolerance of %g, ", (double)ts->rtol));
1945:     if (ts->vatol) PetscCall(PetscViewerASCIIPrintf(viewer, "using vector of absolute error tolerances\n"));
1946:     else PetscCall(PetscViewerASCIIPrintf(viewer, "using absolute error tolerance of %g\n", (double)ts->atol));
1947:     PetscCall(PetscViewerASCIIPushTab(viewer));
1948:     PetscCall(TSAdaptView(ts->adapt, viewer));
1949:     PetscCall(PetscViewerASCIIPopTab(viewer));
1950:   } else if (isstring) {
1951:     PetscCall(TSGetType(ts, &type));
1952:     PetscCall(PetscViewerStringSPrintf(viewer, " TSType: %-7.7s", type));
1953:     PetscTryTypeMethod(ts, view, viewer);
1954:   } else if (isbinary) {
1955:     PetscInt    classid = TS_FILE_CLASSID;
1956:     MPI_Comm    comm;
1957:     PetscMPIInt rank;
1958:     char        type[256];

1960:     PetscCall(PetscObjectGetComm((PetscObject)ts, &comm));
1961:     PetscCallMPI(MPI_Comm_rank(comm, &rank));
1962:     if (rank == 0) {
1963:       PetscCall(PetscViewerBinaryWrite(viewer, &classid, 1, PETSC_INT));
1964:       PetscCall(PetscStrncpy(type, ((PetscObject)ts)->type_name, 256));
1965:       PetscCall(PetscViewerBinaryWrite(viewer, type, 256, PETSC_CHAR));
1966:     }
1967:     PetscTryTypeMethod(ts, view, viewer);
1968:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
1969:     PetscCall(DMView(ts->dm, viewer));
1970:     PetscCall(VecView(ts->vec_sol, viewer));
1971:     PetscCall(DMGetDMTS(ts->dm, &sdm));
1972:     PetscCall(DMTSView(sdm, viewer));
1973:   } else if (isdraw) {
1974:     PetscDraw draw;
1975:     char      str[36];
1976:     PetscReal x, y, bottom, h;

1978:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
1979:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
1980:     PetscCall(PetscStrncpy(str, "TS: ", sizeof(str)));
1981:     PetscCall(PetscStrlcat(str, ((PetscObject)ts)->type_name, sizeof(str)));
1982:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_BLACK, PETSC_DRAW_BLACK, str, NULL, &h));
1983:     bottom = y - h;
1984:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
1985:     PetscTryTypeMethod(ts, view, viewer);
1986:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
1987:     if (ts->snes) PetscCall(SNESView(ts->snes, viewer));
1988:     PetscCall(PetscDrawPopCurrentPoint(draw));
1989: #if defined(PETSC_HAVE_SAWS)
1990:   } else if (issaws) {
1991:     PetscMPIInt rank;
1992:     const char *name;

1994:     PetscCall(PetscObjectGetName((PetscObject)ts, &name));
1995:     PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
1996:     if (!((PetscObject)ts)->amsmem && rank == 0) {
1997:       char dir[1024];

1999:       PetscCall(PetscObjectViewSAWs((PetscObject)ts, viewer));
2000:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time_step", name));
2001:       PetscCallSAWs(SAWs_Register, (dir, &ts->steps, 1, SAWs_READ, SAWs_INT));
2002:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time", name));
2003:       PetscCallSAWs(SAWs_Register, (dir, &ts->ptime, 1, SAWs_READ, SAWs_DOUBLE));
2004:     }
2005:     PetscTryTypeMethod(ts, view, viewer);
2006: #endif
2007:   }
2008:   if (ts->snes && ts->usessnes) {
2009:     PetscCall(PetscViewerASCIIPushTab(viewer));
2010:     PetscCall(SNESView(ts->snes, viewer));
2011:     PetscCall(PetscViewerASCIIPopTab(viewer));
2012:   }
2013:   PetscCall(DMGetDMTS(ts->dm, &sdm));
2014:   PetscCall(DMTSView(sdm, viewer));

2016:   PetscCall(PetscViewerASCIIPushTab(viewer));
2017:   PetscCall(PetscObjectTypeCompare((PetscObject)ts, TSSUNDIALS, &issundials));
2018:   PetscCall(PetscViewerASCIIPopTab(viewer));
2019:   PetscFunctionReturn(PETSC_SUCCESS);
2020: }

2022: /*@
2023:   TSSetApplicationContext - Sets an optional user-defined context for the timesteppers that may be accessed, for example inside the user provided
2024:   `TS` callbacks with `TSGetApplicationContext()`

2026:   Logically Collective

2028:   Input Parameters:
2029: + ts  - the `TS` context obtained from `TSCreate()`
2030: - ctx - user context

2032:   Level: intermediate

2034:   Fortran Note:
2035:   This only works when `ctx` is a Fortran derived type (it cannot be a `PetscObject`), we recommend writing a Fortran interface definition for this
2036:   function that tells the Fortran compiler the derived data type that is passed in as the `ctx` argument. See `TSGetApplicationContext()` for
2037:   an example.

2039: .seealso: [](ch_ts), `TS`, `TSGetApplicationContext()`
2040: @*/
2041: PetscErrorCode TSSetApplicationContext(TS ts, PeCtx ctx)
2042: {
2043:   PetscFunctionBegin;
2045:   ts->ctx = ctx;
2046:   PetscFunctionReturn(PETSC_SUCCESS);
2047: }

2049: /*@
2050:   TSGetApplicationContext - Gets the user-defined context for the
2051:   timestepper that was set with `TSSetApplicationContext()`

2053:   Not Collective

2055:   Input Parameter:
2056: . ts - the `TS` context obtained from `TSCreate()`

2058:   Output Parameter:
2059: . ctx - a pointer to the user context

2061:   Level: intermediate

2063:   Fortran Notes:
2064:   This only works when the context is a Fortran derived type (it cannot be a `PetscObject`) and you **must** write a Fortran interface definition for this
2065:   function that tells the Fortran compiler the derived data type that is returned as the `ctx` argument. For example,
2066: .vb
2067:   Interface TSGetApplicationContext
2068:     Subroutine TSGetApplicationContext(ts,ctx,ierr)
2069:   #include <petsc/finclude/petscts.h>
2070:       use petscts
2071:       TS ts
2072:       type(tUsertype), pointer :: ctx
2073:       PetscErrorCode ierr
2074:     End Subroutine
2075:   End Interface TSGetApplicationContext
2076: .ve

2078:   The prototype for `ctx` must be
2079: .vb
2080:   type(tUsertype), pointer :: ctx
2081: .ve

2083: .seealso: [](ch_ts), `TS`, `TSSetApplicationContext()`
2084: @*/
2085: PetscErrorCode TSGetApplicationContext(TS ts, void *ctx)
2086: {
2087:   PetscFunctionBegin;
2089:   *(void **)ctx = ts->ctx;
2090:   PetscFunctionReturn(PETSC_SUCCESS);
2091: }

2093: /*@
2094:   TSGetStepNumber - Gets the number of time steps completed.

2096:   Not Collective

2098:   Input Parameter:
2099: . ts - the `TS` context obtained from `TSCreate()`

2101:   Output Parameter:
2102: . steps - number of steps completed so far

2104:   Level: intermediate

2106: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetTimeStep()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`
2107: @*/
2108: PetscErrorCode TSGetStepNumber(TS ts, PetscInt *steps)
2109: {
2110:   PetscFunctionBegin;
2112:   PetscAssertPointer(steps, 2);
2113:   *steps = ts->steps;
2114:   PetscFunctionReturn(PETSC_SUCCESS);
2115: }

2117: /*@
2118:   TSSetStepNumber - Sets the number of steps completed.

2120:   Logically Collective

2122:   Input Parameters:
2123: + ts    - the `TS` context
2124: - steps - number of steps completed so far

2126:   Level: developer

2128:   Note:
2129:   For most uses of the `TS` solvers the user need not explicitly call
2130:   `TSSetStepNumber()`, as the step counter is appropriately updated in
2131:   `TSSolve()`/`TSStep()`/`TSRollBack()`. Power users may call this routine to
2132:   reinitialize timestepping by setting the step counter to zero (and time
2133:   to the initial time) to solve a similar problem with different initial
2134:   conditions or parameters. Other possible use case is to continue
2135:   timestepping from a previously interrupted run in such a way that `TS`
2136:   monitors will be called with a initial nonzero step counter.

2138: .seealso: [](ch_ts), `TS`, `TSGetStepNumber()`, `TSSetTime()`, `TSSetTimeStep()`, `TSSetSolution()`
2139: @*/
2140: PetscErrorCode TSSetStepNumber(TS ts, PetscInt steps)
2141: {
2142:   PetscFunctionBegin;
2145:   PetscCheck(steps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Step number must be non-negative");
2146:   ts->steps = steps;
2147:   PetscFunctionReturn(PETSC_SUCCESS);
2148: }

2150: /*@
2151:   TSSetTimeStep - Allows one to reset the timestep at any time.

2153:   Logically Collective

2155:   Input Parameters:
2156: + ts        - the `TS` context obtained from `TSCreate()`
2157: - time_step - the size of the timestep

2159:   Options Database Key:
2160: . -ts_time_step <dt> - provide the initial time step

2162:   Level: intermediate

2164:   Notes:
2165:   This is only a suggestion, the actual initial time step used may differ

2167:   If this is called after `TSSetUp()`, it will not change the initial time step value printed by `TSView()`

2169: .seealso: [](ch_ts), `TS`, `TSPSEUDO`, `TSGetTimeStep()`, `TSSetTime()`
2170: @*/
2171: PetscErrorCode TSSetTimeStep(TS ts, PetscReal time_step)
2172: {
2173:   PetscFunctionBegin;
2176:   ts->time_step = time_step;
2177:   if (ts->setupcalled == PETSC_FALSE) ts->initial_time_step = time_step;
2178:   PetscFunctionReturn(PETSC_SUCCESS);
2179: }

2181: /*@
2182:   TSSetExactFinalTime - Determines whether to adapt the final time step to
2183:   match the exact final time, to interpolate the solution to the exact final time,
2184:   or to just return at the final time `TS` computed (which may be slightly larger
2185:   than the requested final time).

2187:   Logically Collective

2189:   Input Parameters:
2190: + ts     - the time-step context
2191: - eftopt - exact final time option
2192: .vb
2193:   TS_EXACTFINALTIME_STEPOVER    - Don't do anything if final time is exceeded, just use it
2194:   TS_EXACTFINALTIME_INTERPOLATE - Interpolate back to final time if the final time is exceeded
2195:   TS_EXACTFINALTIME_MATCHSTEP   - Adapt final time step to ensure the computed final time exactly equals the requested final time
2196: .ve

2198:   Options Database Key:
2199: . -ts_exact_final_time <stepover,interpolate,matchstep> - select the final step approach at runtime

2201:   Level: beginner

2203:   Note:
2204:   If you use the option `TS_EXACTFINALTIME_STEPOVER` the solution may be at a very different time
2205:   then the final time you selected.

2207: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSGetExactFinalTime()`
2208: @*/
2209: PetscErrorCode TSSetExactFinalTime(TS ts, TSExactFinalTimeOption eftopt)
2210: {
2211:   PetscFunctionBegin;
2214:   ts->exact_final_time = eftopt;
2215:   PetscFunctionReturn(PETSC_SUCCESS);
2216: }

2218: /*@
2219:   TSGetExactFinalTime - Gets the exact final time option set with `TSSetExactFinalTime()`

2221:   Not Collective

2223:   Input Parameter:
2224: . ts - the `TS` context

2226:   Output Parameter:
2227: . eftopt - exact final time option

2229:   Level: beginner

2231: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSSetExactFinalTime()`
2232: @*/
2233: PetscErrorCode TSGetExactFinalTime(TS ts, TSExactFinalTimeOption *eftopt)
2234: {
2235:   PetscFunctionBegin;
2237:   PetscAssertPointer(eftopt, 2);
2238:   *eftopt = ts->exact_final_time;
2239:   PetscFunctionReturn(PETSC_SUCCESS);
2240: }

2242: /*@
2243:   TSGetTimeStep - Gets the current timestep size.

2245:   Not Collective

2247:   Input Parameter:
2248: . ts - the `TS` context obtained from `TSCreate()`

2250:   Output Parameter:
2251: . dt - the current timestep size

2253:   Level: intermediate

2255: .seealso: [](ch_ts), `TS`, `TSSetTimeStep()`, `TSGetTime()`
2256: @*/
2257: PetscErrorCode TSGetTimeStep(TS ts, PetscReal *dt)
2258: {
2259:   PetscFunctionBegin;
2261:   PetscAssertPointer(dt, 2);
2262:   *dt = ts->time_step;
2263:   PetscFunctionReturn(PETSC_SUCCESS);
2264: }

2266: /*@
2267:   TSGetSolution - Returns the solution at the present timestep. It
2268:   is valid to call this routine inside the function that you are evaluating
2269:   in order to move to the new timestep. This vector not changed until
2270:   the solution at the next timestep has been calculated.

2272:   Not Collective, but v returned is parallel if ts is parallel

2274:   Input Parameter:
2275: . ts - the `TS` context obtained from `TSCreate()`

2277:   Output Parameter:
2278: . v - the vector containing the solution

2280:   Level: intermediate

2282:   Note:
2283:   If you used `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`); this does not return the solution at the requested
2284:   final time. It returns the solution at the next timestep.

2286: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetSolutionComponents()`, `TSSetSolutionFunction()`
2287: @*/
2288: PetscErrorCode TSGetSolution(TS ts, Vec *v)
2289: {
2290:   PetscFunctionBegin;
2292:   PetscAssertPointer(v, 2);
2293:   *v = ts->vec_sol;
2294:   PetscFunctionReturn(PETSC_SUCCESS);
2295: }

2297: /*@
2298:   TSGetSolutionComponents - Returns any solution components at the present
2299:   timestep, if available for the time integration method being used.
2300:   Solution components are quantities that share the same size and
2301:   structure as the solution vector.

2303:   Not Collective, but v returned is parallel if ts is parallel

2305:   Input Parameters:
2306: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2307: . n  - If v is `NULL`, then the number of solution components is
2308:        returned through n, else the n-th solution component is
2309:        returned in v.
2310: - v  - the vector containing the n-th solution component
2311:        (may be `NULL` to use this function to find out
2312:         the number of solutions components).

2314:   Level: advanced

2316: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2317: @*/
2318: PetscErrorCode TSGetSolutionComponents(TS ts, PetscInt *n, Vec *v)
2319: {
2320:   PetscFunctionBegin;
2322:   if (!ts->ops->getsolutioncomponents) *n = 0;
2323:   else PetscUseTypeMethod(ts, getsolutioncomponents, n, v);
2324:   PetscFunctionReturn(PETSC_SUCCESS);
2325: }

2327: /*@
2328:   TSGetAuxSolution - Returns an auxiliary solution at the present
2329:   timestep, if available for the time integration method being used.

2331:   Not Collective, but v returned is parallel if ts is parallel

2333:   Input Parameters:
2334: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2335: - v  - the vector containing the auxiliary solution

2337:   Level: intermediate

2339: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2340: @*/
2341: PetscErrorCode TSGetAuxSolution(TS ts, Vec *v)
2342: {
2343:   PetscFunctionBegin;
2345:   if (ts->ops->getauxsolution) PetscUseTypeMethod(ts, getauxsolution, v);
2346:   else PetscCall(VecZeroEntries(*v));
2347:   PetscFunctionReturn(PETSC_SUCCESS);
2348: }

2350: /*@
2351:   TSGetTimeError - Returns the estimated error vector, if the chosen
2352:   `TSType` has an error estimation functionality and `TSSetTimeError()` was called

2354:   Not Collective, but v returned is parallel if ts is parallel

2356:   Input Parameters:
2357: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2358: . n  - current estimate (n=0) or previous one (n=-1)
2359: - v  - the vector containing the error (same size as the solution).

2361:   Level: intermediate

2363:   Note:
2364:   MUST call after `TSSetUp()`

2366: .seealso: [](ch_ts), `TSGetSolution()`, `TSSetTimeError()`
2367: @*/
2368: PetscErrorCode TSGetTimeError(TS ts, PetscInt n, Vec *v)
2369: {
2370:   PetscFunctionBegin;
2372:   if (ts->ops->gettimeerror) PetscUseTypeMethod(ts, gettimeerror, n, v);
2373:   else PetscCall(VecZeroEntries(*v));
2374:   PetscFunctionReturn(PETSC_SUCCESS);
2375: }

2377: /*@
2378:   TSSetTimeError - Sets the estimated error vector, if the chosen
2379:   `TSType` has an error estimation functionality. This can be used
2380:   to restart such a time integrator with a given error vector.

2382:   Not Collective, but v returned is parallel if ts is parallel

2384:   Input Parameters:
2385: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2386: - v  - the vector containing the error (same size as the solution).

2388:   Level: intermediate

2390: .seealso: [](ch_ts), `TS`, `TSSetSolution()`, `TSGetTimeError()`
2391: @*/
2392: PetscErrorCode TSSetTimeError(TS ts, Vec v)
2393: {
2394:   PetscFunctionBegin;
2396:   PetscCheck(ts->setupcalled, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetUp() first");
2397:   PetscTryTypeMethod(ts, settimeerror, v);
2398:   PetscFunctionReturn(PETSC_SUCCESS);
2399: }

2401: /* ----- Routines to initialize and destroy a timestepper ---- */
2402: /*@
2403:   TSSetProblemType - Sets the type of problem to be solved.

2405:   Not collective

2407:   Input Parameters:
2408: + ts   - The `TS`
2409: - type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2410: .vb
2411:          U_t - A U = 0      (linear)
2412:          U_t - A(t) U = 0   (linear)
2413:          F(t,U,U_t) = 0     (nonlinear)
2414: .ve

2416:   Level: beginner

2418: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2419: @*/
2420: PetscErrorCode TSSetProblemType(TS ts, TSProblemType type)
2421: {
2422:   PetscFunctionBegin;
2424:   ts->problem_type = type;
2425:   if (type == TS_LINEAR) {
2426:     SNES snes;
2427:     PetscCall(TSGetSNES(ts, &snes));
2428:     PetscCall(SNESSetType(snes, SNESKSPONLY));
2429:   }
2430:   PetscFunctionReturn(PETSC_SUCCESS);
2431: }

2433: /*@
2434:   TSGetProblemType - Gets the type of problem to be solved.

2436:   Not collective

2438:   Input Parameter:
2439: . ts - The `TS`

2441:   Output Parameter:
2442: . type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2443: .vb
2444:          M U_t = A U
2445:          M(t) U_t = A(t) U
2446:          F(t,U,U_t)
2447: .ve

2449:   Level: beginner

2451: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2452: @*/
2453: PetscErrorCode TSGetProblemType(TS ts, TSProblemType *type)
2454: {
2455:   PetscFunctionBegin;
2457:   PetscAssertPointer(type, 2);
2458:   *type = ts->problem_type;
2459:   PetscFunctionReturn(PETSC_SUCCESS);
2460: }

2462: /*
2463:     Attempt to check/preset a default value for the exact final time option. This is needed at the beginning of TSSolve() and in TSSetUp()
2464: */
2465: static PetscErrorCode TSSetExactFinalTimeDefault(TS ts)
2466: {
2467:   PetscBool isnone;

2469:   PetscFunctionBegin;
2470:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2471:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2473:   PetscCall(PetscObjectTypeCompare((PetscObject)ts->adapt, TSADAPTNONE, &isnone));
2474:   if (!isnone && ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_MATCHSTEP;
2475:   else if (ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_INTERPOLATE;
2476:   PetscFunctionReturn(PETSC_SUCCESS);
2477: }

2479: /*@
2480:   TSSetUp - Sets up the internal data structures for the later use of a timestepper.

2482:   Collective

2484:   Input Parameter:
2485: . ts - the `TS` context obtained from `TSCreate()`

2487:   Level: advanced

2489:   Note:
2490:   For basic use of the `TS` solvers the user need not explicitly call
2491:   `TSSetUp()`, since these actions will automatically occur during
2492:   the call to `TSStep()` or `TSSolve()`.  However, if one wishes to control this
2493:   phase separately, `TSSetUp()` should be called after `TSCreate()`
2494:   and optional routines of the form TSSetXXX(), but before `TSStep()` and `TSSolve()`.

2496: .seealso: [](ch_ts), `TSCreate()`, `TS`, `TSStep()`, `TSDestroy()`, `TSSolve()`
2497: @*/
2498: PetscErrorCode TSSetUp(TS ts)
2499: {
2500:   DM dm;
2501:   PetscErrorCode (*func)(SNES, Vec, Vec, void *);
2502:   PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *);
2503:   TSIFunctionFn   *ifun;
2504:   TSIJacobianFn   *ijac;
2505:   TSI2JacobianFn  *i2jac;
2506:   TSRHSJacobianFn *rhsjac;

2508:   PetscFunctionBegin;
2510:   if (ts->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);

2512:   if (!((PetscObject)ts)->type_name) {
2513:     PetscCall(TSGetIFunction(ts, NULL, &ifun, NULL));
2514:     PetscCall(TSSetType(ts, ifun ? TSBEULER : TSEULER));
2515:   }

2517:   if (!ts->vec_sol) {
2518:     PetscCheck(ts->dm, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetSolution() first");
2519:     PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
2520:   }

2522:   if (!ts->Jacp && ts->Jacprhs) { /* IJacobianP shares the same matrix with RHSJacobianP if only RHSJacobianP is provided */
2523:     PetscCall(PetscObjectReference((PetscObject)ts->Jacprhs));
2524:     ts->Jacp = ts->Jacprhs;
2525:   }

2527:   if (ts->quadraturets) {
2528:     PetscCall(TSSetUp(ts->quadraturets));
2529:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2530:     PetscCall(VecDuplicate(ts->quadraturets->vec_sol, &ts->vec_costintegrand));
2531:   }

2533:   PetscCall(TSGetRHSJacobian(ts, NULL, NULL, &rhsjac, NULL));
2534:   if (rhsjac == TSComputeRHSJacobianConstant) {
2535:     Mat  Amat, Pmat;
2536:     SNES snes;
2537:     PetscCall(TSGetSNES(ts, &snes));
2538:     PetscCall(SNESGetJacobian(snes, &Amat, &Pmat, NULL, NULL));
2539:     /* Matching matrices implies that an IJacobian is NOT set, because if it had been set, the IJacobian's matrix would
2540:      * have displaced the RHS matrix */
2541:     if (Amat && Amat == ts->Arhs) {
2542:       /* 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 */
2543:       PetscCall(MatDuplicate(ts->Arhs, MAT_COPY_VALUES, &Amat));
2544:       PetscCall(SNESSetJacobian(snes, Amat, NULL, NULL, NULL));
2545:       PetscCall(MatDestroy(&Amat));
2546:     }
2547:     if (Pmat && Pmat == ts->Brhs) {
2548:       PetscCall(MatDuplicate(ts->Brhs, MAT_COPY_VALUES, &Pmat));
2549:       PetscCall(SNESSetJacobian(snes, NULL, Pmat, NULL, NULL));
2550:       PetscCall(MatDestroy(&Pmat));
2551:     }
2552:   }

2554:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2555:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2557:   PetscTryTypeMethod(ts, setup);

2559:   PetscCall(TSSetExactFinalTimeDefault(ts));

2561:   /* In the case where we've set a DMTSFunction or what have you, we need the default SNESFunction
2562:      to be set right but can't do it elsewhere due to the overreliance on ctx=ts.
2563:    */
2564:   PetscCall(TSGetDM(ts, &dm));
2565:   PetscCall(DMSNESGetFunction(dm, &func, NULL));
2566:   if (!func) PetscCall(DMSNESSetFunction(dm, SNESTSFormFunction, ts));

2568:   /* If the SNES doesn't have a jacobian set and the TS has an ijacobian or rhsjacobian set, set the SNES to use it.
2569:      Otherwise, the SNES will use coloring internally to form the Jacobian.
2570:    */
2571:   PetscCall(DMSNESGetJacobian(dm, &jac, NULL));
2572:   PetscCall(DMTSGetIJacobian(dm, &ijac, NULL));
2573:   PetscCall(DMTSGetI2Jacobian(dm, &i2jac, NULL));
2574:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjac, NULL));
2575:   if (!jac && (ijac || i2jac || rhsjac)) PetscCall(DMSNESSetJacobian(dm, SNESTSFormJacobian, ts));

2577:   /* if time integration scheme has a starting method, call it */
2578:   PetscTryTypeMethod(ts, startingmethod);

2580:   ts->setupcalled = PETSC_TRUE;
2581:   PetscFunctionReturn(PETSC_SUCCESS);
2582: }

2584: /*@
2585:   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

2587:   Collective

2589:   Input Parameter:
2590: . ts - the `TS` context obtained from `TSCreate()`

2592:   Level: developer

2594:   Notes:
2595:   Any options set on the `TS` object, including those set with `TSSetFromOptions()` remain.

2597:   See also `TSSetResize()` to change the size of the system being integrated (for example by adaptive mesh refinement) during the time integration.

2599: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSetResize()`
2600: @*/
2601: PetscErrorCode TSReset(TS ts)
2602: {
2603:   TS_RHSSplitLink ilink = ts->tsrhssplit, next;

2605:   PetscFunctionBegin;

2608:   PetscTryTypeMethod(ts, reset);
2609:   if (ts->snes) PetscCall(SNESReset(ts->snes));
2610:   if (ts->adapt) PetscCall(TSAdaptReset(ts->adapt));

2612:   PetscCall(MatDestroy(&ts->Arhs));
2613:   PetscCall(MatDestroy(&ts->Brhs));
2614:   PetscCall(VecDestroy(&ts->Frhs));
2615:   PetscCall(VecDestroy(&ts->vec_sol));
2616:   PetscCall(VecDestroy(&ts->vec_sol0));
2617:   PetscCall(VecDestroy(&ts->vec_dot));
2618:   PetscCall(VecDestroy(&ts->vatol));
2619:   PetscCall(VecDestroy(&ts->vrtol));
2620:   PetscCall(VecDestroyVecs(ts->nwork, &ts->work));

2622:   PetscCall(MatDestroy(&ts->Jacprhs));
2623:   PetscCall(MatDestroy(&ts->Jacp));
2624:   if (ts->forward_solve) PetscCall(TSForwardReset(ts));
2625:   if (ts->quadraturets) {
2626:     PetscCall(TSReset(ts->quadraturets));
2627:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2628:   }
2629:   while (ilink) {
2630:     next = ilink->next;
2631:     PetscCall(TSDestroy(&ilink->ts));
2632:     PetscCall(PetscFree(ilink->splitname));
2633:     PetscCall(ISDestroy(&ilink->is));
2634:     PetscCall(PetscFree(ilink));
2635:     ilink = next;
2636:   }
2637:   ts->tsrhssplit     = NULL;
2638:   ts->num_rhs_splits = 0;
2639:   if (ts->eval_times) {
2640:     PetscCall(PetscFree(ts->eval_times->time_points));
2641:     PetscCall(PetscFree(ts->eval_times->sol_times));
2642:     PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
2643:     PetscCall(PetscFree(ts->eval_times));
2644:   }
2645:   ts->rhsjacobian.time  = PETSC_MIN_REAL;
2646:   ts->rhsjacobian.scale = 1.0;
2647:   ts->ijacobian.shift   = 1.0;
2648:   ts->setupcalled       = PETSC_FALSE;
2649:   PetscFunctionReturn(PETSC_SUCCESS);
2650: }

2652: static PetscErrorCode TSResizeReset(TS);

2654: /*@
2655:   TSDestroy - Destroys the timestepper context that was created
2656:   with `TSCreate()`.

2658:   Collective

2660:   Input Parameter:
2661: . ts - the `TS` context obtained from `TSCreate()`

2663:   Level: beginner

2665: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSSolve()`
2666: @*/
2667: PetscErrorCode TSDestroy(TS *ts)
2668: {
2669:   PetscFunctionBegin;
2670:   if (!*ts) PetscFunctionReturn(PETSC_SUCCESS);
2672:   if (--((PetscObject)*ts)->refct > 0) {
2673:     *ts = NULL;
2674:     PetscFunctionReturn(PETSC_SUCCESS);
2675:   }

2677:   PetscCall(TSReset(*ts));
2678:   PetscCall(TSAdjointReset(*ts));
2679:   if ((*ts)->forward_solve) PetscCall(TSForwardReset(*ts));
2680:   PetscCall(TSResizeReset(*ts));

2682:   /* if memory was published with SAWs then destroy it */
2683:   PetscCall(PetscObjectSAWsViewOff((PetscObject)*ts));
2684:   PetscTryTypeMethod(*ts, destroy);

2686:   PetscCall(TSTrajectoryDestroy(&(*ts)->trajectory));

2688:   PetscCall(TSAdaptDestroy(&(*ts)->adapt));
2689:   PetscCall(TSEventDestroy(&(*ts)->event));

2691:   PetscCall(SNESDestroy(&(*ts)->snes));
2692:   PetscCall(SNESDestroy(&(*ts)->snesrhssplit));
2693:   PetscCall(DMDestroy(&(*ts)->dm));
2694:   PetscCall(TSMonitorCancel(*ts));
2695:   PetscCall(TSAdjointMonitorCancel(*ts));

2697:   PetscCall(TSDestroy(&(*ts)->quadraturets));
2698:   PetscCall(PetscHeaderDestroy(ts));
2699:   PetscFunctionReturn(PETSC_SUCCESS);
2700: }

2702: /*@
2703:   TSGetSNES - Returns the `SNES` (nonlinear solver) associated with
2704:   a `TS` (timestepper) context. Valid only for nonlinear problems.

2706:   Not Collective, but snes is parallel if ts is parallel

2708:   Input Parameter:
2709: . ts - the `TS` context obtained from `TSCreate()`

2711:   Output Parameter:
2712: . snes - the nonlinear solver context

2714:   Level: beginner

2716:   Notes:
2717:   The user can then directly manipulate the `SNES` context to set various
2718:   options, etc.  Likewise, the user can then extract and manipulate the
2719:   `KSP`, and `PC` contexts as well.

2721:   `TSGetSNES()` does not work for integrators that do not use `SNES`; in
2722:   this case `TSGetSNES()` returns `NULL` in `snes`.

2724: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`
2725: @*/
2726: PetscErrorCode TSGetSNES(TS ts, SNES *snes)
2727: {
2728:   PetscFunctionBegin;
2730:   PetscAssertPointer(snes, 2);
2731:   if (!ts->snes) {
2732:     PetscCall(SNESCreate(PetscObjectComm((PetscObject)ts), &ts->snes));
2733:     PetscCall(PetscObjectSetOptions((PetscObject)ts->snes, ((PetscObject)ts)->options));
2734:     PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2735:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->snes, (PetscObject)ts, 1));
2736:     if (ts->dm) PetscCall(SNESSetDM(ts->snes, ts->dm));
2737:     if (ts->problem_type == TS_LINEAR) PetscCall(SNESSetType(ts->snes, SNESKSPONLY));
2738:   }
2739:   *snes = ts->snes;
2740:   PetscFunctionReturn(PETSC_SUCCESS);
2741: }

2743: /*@
2744:   TSSetSNES - Set the `SNES` (nonlinear solver) to be used by the `TS` timestepping context

2746:   Collective

2748:   Input Parameters:
2749: + ts   - the `TS` context obtained from `TSCreate()`
2750: - snes - the nonlinear solver context

2752:   Level: developer

2754:   Note:
2755:   Most users should have the `TS` created by calling `TSGetSNES()`

2757: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetSNES()`
2758: @*/
2759: PetscErrorCode TSSetSNES(TS ts, SNES snes)
2760: {
2761:   PetscErrorCode (*func)(SNES, Vec, Mat, Mat, void *);

2763:   PetscFunctionBegin;
2766:   PetscCall(PetscObjectReference((PetscObject)snes));
2767:   PetscCall(SNESDestroy(&ts->snes));

2769:   ts->snes = snes;

2771:   PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2772:   PetscCall(SNESGetJacobian(ts->snes, NULL, NULL, &func, NULL));
2773:   if (func == SNESTSFormJacobian) PetscCall(SNESSetJacobian(ts->snes, NULL, NULL, SNESTSFormJacobian, ts));
2774:   PetscFunctionReturn(PETSC_SUCCESS);
2775: }

2777: /*@
2778:   TSGetKSP - Returns the `KSP` (linear solver) associated with
2779:   a `TS` (timestepper) context.

2781:   Not Collective, but `ksp` is parallel if `ts` is parallel

2783:   Input Parameter:
2784: . ts - the `TS` context obtained from `TSCreate()`

2786:   Output Parameter:
2787: . ksp - the nonlinear solver context

2789:   Level: beginner

2791:   Notes:
2792:   The user can then directly manipulate the `KSP` context to set various
2793:   options, etc.  Likewise, the user can then extract and manipulate the
2794:   `PC` context as well.

2796:   `TSGetKSP()` does not work for integrators that do not use `KSP`;
2797:   in this case `TSGetKSP()` returns `NULL` in `ksp`.

2799: .seealso: [](ch_ts), `TS`, `SNES`, `KSP`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetSNES()`
2800: @*/
2801: PetscErrorCode TSGetKSP(TS ts, KSP *ksp)
2802: {
2803:   SNES snes;

2805:   PetscFunctionBegin;
2807:   PetscAssertPointer(ksp, 2);
2808:   PetscCheck(((PetscObject)ts)->type_name, PETSC_COMM_SELF, PETSC_ERR_ARG_NULL, "KSP is not created yet. Call TSSetType() first");
2809:   PetscCheck(ts->problem_type == TS_LINEAR, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Linear only; use TSGetSNES()");
2810:   PetscCall(TSGetSNES(ts, &snes));
2811:   PetscCall(SNESGetKSP(snes, ksp));
2812:   PetscFunctionReturn(PETSC_SUCCESS);
2813: }

2815: /* ----------- Routines to set solver parameters ---------- */

2817: /*@
2818:   TSSetMaxSteps - Sets the maximum number of steps to use.

2820:   Logically Collective

2822:   Input Parameters:
2823: + ts       - the `TS` context obtained from `TSCreate()`
2824: - maxsteps - maximum number of steps to use

2826:   Options Database Key:
2827: . -ts_max_steps <maxsteps> - Sets maxsteps

2829:   Level: intermediate

2831:   Note:
2832:   Use `PETSC_DETERMINE` to reset the maximum number of steps to the default from when the object's type was set

2834:   The default maximum number of steps is 5,000

2836:   Fortran Note:
2837:   Use `PETSC_DETERMINE_INTEGER`

2839: .seealso: [](ch_ts), `TS`, `TSGetMaxSteps()`, `TSSetMaxTime()`, `TSSetExactFinalTime()`
2840: @*/
2841: PetscErrorCode TSSetMaxSteps(TS ts, PetscInt maxsteps)
2842: {
2843:   PetscFunctionBegin;
2846:   if (maxsteps == PETSC_DETERMINE) {
2847:     ts->max_steps = ts->default_max_steps;
2848:   } else {
2849:     PetscCheck(maxsteps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of steps must be non-negative");
2850:     ts->max_steps = maxsteps;
2851:   }
2852:   PetscFunctionReturn(PETSC_SUCCESS);
2853: }

2855: /*@
2856:   TSGetMaxSteps - Gets the maximum number of steps to use.

2858:   Not Collective

2860:   Input Parameter:
2861: . ts - the `TS` context obtained from `TSCreate()`

2863:   Output Parameter:
2864: . maxsteps - maximum number of steps to use

2866:   Level: advanced

2868: .seealso: [](ch_ts), `TS`, `TSSetMaxSteps()`, `TSGetMaxTime()`, `TSSetMaxTime()`
2869: @*/
2870: PetscErrorCode TSGetMaxSteps(TS ts, PetscInt *maxsteps)
2871: {
2872:   PetscFunctionBegin;
2874:   PetscAssertPointer(maxsteps, 2);
2875:   *maxsteps = ts->max_steps;
2876:   PetscFunctionReturn(PETSC_SUCCESS);
2877: }

2879: /*@
2880:   TSSetRunSteps - Sets the maximum number of steps to take in each call to `TSSolve()`.

2882:   If the step count when `TSSolve()` is `start_step`, this will stop the simulation once `current_step - start_step >= run_steps`.
2883:   Comparatively, `TSSetMaxSteps()` will stop if `current_step >= max_steps`.
2884:   The simulation will stop when either condition is reached.

2886:   Logically Collective

2888:   Input Parameters:
2889: + ts       - the `TS` context obtained from `TSCreate()`
2890: - runsteps - maximum number of steps to take in each call to `TSSolve()`;

2892:   Options Database Key:
2893: . -ts_run_steps <runsteps> - Sets runsteps

2895:   Level: intermediate

2897:   Note:
2898:   The default is `PETSC_UNLIMITED`

2900: .seealso: [](ch_ts), `TS`, `TSGetRunSteps()`, `TSSetMaxTime()`, `TSSetExactFinalTime()`, `TSSetMaxSteps()`
2901: @*/
2902: PetscErrorCode TSSetRunSteps(TS ts, PetscInt runsteps)
2903: {
2904:   PetscFunctionBegin;
2907:   if (runsteps == PETSC_DETERMINE) {
2908:     ts->run_steps = PETSC_UNLIMITED;
2909:   } else {
2910:     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");
2911:     ts->run_steps = runsteps;
2912:   }
2913:   PetscFunctionReturn(PETSC_SUCCESS);
2914: }

2916: /*@
2917:   TSGetRunSteps - Gets the maximum number of steps to take in each call to `TSSolve()`.

2919:   Not Collective

2921:   Input Parameter:
2922: . ts - the `TS` context obtained from `TSCreate()`

2924:   Output Parameter:
2925: . runsteps - maximum number of steps to take in each call to `TSSolve`.

2927:   Level: advanced

2929: .seealso: [](ch_ts), `TS`, `TSSetRunSteps()`, `TSGetMaxTime()`, `TSSetMaxTime()`, `TSGetMaxSteps()`
2930: @*/
2931: PetscErrorCode TSGetRunSteps(TS ts, PetscInt *runsteps)
2932: {
2933:   PetscFunctionBegin;
2935:   PetscAssertPointer(runsteps, 2);
2936:   *runsteps = ts->run_steps;
2937:   PetscFunctionReturn(PETSC_SUCCESS);
2938: }

2940: /*@
2941:   TSSetMaxTime - Sets the maximum (or final) time for timestepping.

2943:   Logically Collective

2945:   Input Parameters:
2946: + ts      - the `TS` context obtained from `TSCreate()`
2947: - maxtime - final time to step to

2949:   Options Database Key:
2950: . -ts_max_time <maxtime> - Sets maxtime

2952:   Level: intermediate

2954:   Notes:
2955:   Use `PETSC_DETERMINE` to reset the maximum time to the default from when the object's type was set

2957:   The default maximum time is 5.0

2959:   Fortran Note:
2960:   Use `PETSC_DETERMINE_REAL`

2962: .seealso: [](ch_ts), `TS`, `TSGetMaxTime()`, `TSSetMaxSteps()`, `TSSetExactFinalTime()`
2963: @*/
2964: PetscErrorCode TSSetMaxTime(TS ts, PetscReal maxtime)
2965: {
2966:   PetscFunctionBegin;
2969:   if (maxtime == PETSC_DETERMINE) {
2970:     ts->max_time = ts->default_max_time;
2971:   } else {
2972:     ts->max_time = maxtime;
2973:   }
2974:   PetscFunctionReturn(PETSC_SUCCESS);
2975: }

2977: /*@
2978:   TSGetMaxTime - Gets the maximum (or final) time for timestepping.

2980:   Not Collective

2982:   Input Parameter:
2983: . ts - the `TS` context obtained from `TSCreate()`

2985:   Output Parameter:
2986: . maxtime - final time to step to

2988:   Level: advanced

2990: .seealso: [](ch_ts), `TS`, `TSSetMaxTime()`, `TSGetMaxSteps()`, `TSSetMaxSteps()`
2991: @*/
2992: PetscErrorCode TSGetMaxTime(TS ts, PetscReal *maxtime)
2993: {
2994:   PetscFunctionBegin;
2996:   PetscAssertPointer(maxtime, 2);
2997:   *maxtime = ts->max_time;
2998:   PetscFunctionReturn(PETSC_SUCCESS);
2999: }

3001: // PetscClangLinter pragma disable: -fdoc-*
3002: /*@
3003:   TSSetInitialTimeStep - Deprecated, use `TSSetTime()` and `TSSetTimeStep()`.

3005:   Level: deprecated

3007: @*/
3008: PetscErrorCode TSSetInitialTimeStep(TS ts, PetscReal initial_time, PetscReal time_step)
3009: {
3010:   PetscFunctionBegin;
3012:   PetscCall(TSSetTime(ts, initial_time));
3013:   PetscCall(TSSetTimeStep(ts, time_step));
3014:   PetscFunctionReturn(PETSC_SUCCESS);
3015: }

3017: // PetscClangLinter pragma disable: -fdoc-*
3018: /*@
3019:   TSGetDuration - Deprecated, use `TSGetMaxSteps()` and `TSGetMaxTime()`.

3021:   Level: deprecated

3023: @*/
3024: PetscErrorCode TSGetDuration(TS ts, PetscInt *maxsteps, PetscReal *maxtime)
3025: {
3026:   PetscFunctionBegin;
3028:   if (maxsteps) {
3029:     PetscAssertPointer(maxsteps, 2);
3030:     *maxsteps = ts->max_steps;
3031:   }
3032:   if (maxtime) {
3033:     PetscAssertPointer(maxtime, 3);
3034:     *maxtime = ts->max_time;
3035:   }
3036:   PetscFunctionReturn(PETSC_SUCCESS);
3037: }

3039: // PetscClangLinter pragma disable: -fdoc-*
3040: /*@
3041:   TSSetDuration - Deprecated, use `TSSetMaxSteps()` and `TSSetMaxTime()`.

3043:   Level: deprecated

3045: @*/
3046: PetscErrorCode TSSetDuration(TS ts, PetscInt maxsteps, PetscReal maxtime)
3047: {
3048:   PetscFunctionBegin;
3049:   if (maxsteps != PETSC_CURRENT) PetscCall(TSSetMaxSteps(ts, maxsteps));
3050:   if (maxtime != (PetscReal)PETSC_CURRENT) PetscCall(TSSetMaxTime(ts, maxtime));
3051:   PetscFunctionReturn(PETSC_SUCCESS);
3052: }

3054: // PetscClangLinter pragma disable: -fdoc-*
3055: /*@
3056:   TSGetTimeStepNumber - Deprecated, use `TSGetStepNumber()`.

3058:   Level: deprecated

3060: @*/
3061: PetscErrorCode TSGetTimeStepNumber(TS ts, PetscInt *steps)
3062: {
3063:   return TSGetStepNumber(ts, steps);
3064: }

3066: // PetscClangLinter pragma disable: -fdoc-*
3067: /*@
3068:   TSGetTotalSteps - Deprecated, use `TSGetStepNumber()`.

3070:   Level: deprecated

3072: @*/
3073: PetscErrorCode TSGetTotalSteps(TS ts, PetscInt *steps)
3074: {
3075:   return TSGetStepNumber(ts, steps);
3076: }

3078: /*@
3079:   TSSetSolution - Sets the initial solution vector
3080:   for use by the `TS` routines.

3082:   Logically Collective

3084:   Input Parameters:
3085: + ts - the `TS` context obtained from `TSCreate()`
3086: - u  - the solution vector

3088:   Level: beginner

3090: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSGetSolution()`, `TSCreate()`
3091: @*/
3092: PetscErrorCode TSSetSolution(TS ts, Vec u)
3093: {
3094:   DM dm;

3096:   PetscFunctionBegin;
3099:   PetscCall(PetscObjectReference((PetscObject)u));
3100:   PetscCall(VecDestroy(&ts->vec_sol));
3101:   ts->vec_sol = u;

3103:   PetscCall(TSGetDM(ts, &dm));
3104:   PetscCall(DMShellSetGlobalVector(dm, u));
3105:   PetscFunctionReturn(PETSC_SUCCESS);
3106: }

3108: /*@C
3109:   TSSetPreStep - Sets the general-purpose function
3110:   called once at the beginning of each time step.

3112:   Logically Collective

3114:   Input Parameters:
3115: + ts   - The `TS` context obtained from `TSCreate()`
3116: - func - The function

3118:   Calling sequence of `func`:
3119: . ts - the `TS` context

3121:   Level: intermediate

3123: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`, `TSStep()`, `TSRestartStep()`
3124: @*/
3125: PetscErrorCode TSSetPreStep(TS ts, PetscErrorCode (*func)(TS ts))
3126: {
3127:   PetscFunctionBegin;
3129:   ts->prestep = func;
3130:   PetscFunctionReturn(PETSC_SUCCESS);
3131: }

3133: /*@
3134:   TSPreStep - Runs the user-defined pre-step function provided with `TSSetPreStep()`

3136:   Collective

3138:   Input Parameter:
3139: . ts - The `TS` context obtained from `TSCreate()`

3141:   Level: developer

3143:   Note:
3144:   `TSPreStep()` is typically used within time stepping implementations,
3145:   so most users would not generally call this routine themselves.

3147: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSPreStage()`, `TSPostStage()`, `TSPostStep()`
3148: @*/
3149: PetscErrorCode TSPreStep(TS ts)
3150: {
3151:   PetscFunctionBegin;
3153:   if (ts->prestep) {
3154:     Vec              U;
3155:     PetscObjectId    idprev;
3156:     PetscBool        sameObject;
3157:     PetscObjectState sprev, spost;

3159:     PetscCall(TSGetSolution(ts, &U));
3160:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3161:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3162:     PetscCallBack("TS callback preset", (*ts->prestep)(ts));
3163:     PetscCall(TSGetSolution(ts, &U));
3164:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3165:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3166:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3167:   }
3168:   PetscFunctionReturn(PETSC_SUCCESS);
3169: }

3171: /*@C
3172:   TSSetPreStage - Sets the general-purpose function
3173:   called once at the beginning of each stage.

3175:   Logically Collective

3177:   Input Parameters:
3178: + ts   - The `TS` context obtained from `TSCreate()`
3179: - func - The function

3181:   Calling sequence of `func`:
3182: + ts        - the `TS` context
3183: - stagetime - the stage time

3185:   Level: intermediate

3187:   Note:
3188:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3189:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3190:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3192: .seealso: [](ch_ts), `TS`, `TSSetPostStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3193: @*/
3194: PetscErrorCode TSSetPreStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime))
3195: {
3196:   PetscFunctionBegin;
3198:   ts->prestage = func;
3199:   PetscFunctionReturn(PETSC_SUCCESS);
3200: }

3202: /*@C
3203:   TSSetPostStage - Sets the general-purpose function
3204:   called once at the end of each stage.

3206:   Logically Collective

3208:   Input Parameters:
3209: + ts   - The `TS` context obtained from `TSCreate()`
3210: - func - The function

3212:   Calling sequence of `func`:
3213: + ts         - the `TS` context
3214: . stagetime  - the stage time
3215: . stageindex - the stage index
3216: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3218:   Level: intermediate

3220:   Note:
3221:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3222:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3223:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3225: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3226: @*/
3227: PetscErrorCode TSSetPostStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime, PetscInt stageindex, Vec *Y))
3228: {
3229:   PetscFunctionBegin;
3231:   ts->poststage = func;
3232:   PetscFunctionReturn(PETSC_SUCCESS);
3233: }

3235: /*@C
3236:   TSSetPostEvaluate - Sets the general-purpose function
3237:   called at the end of each step evaluation.

3239:   Logically Collective

3241:   Input Parameters:
3242: + ts   - The `TS` context obtained from `TSCreate()`
3243: - func - The function

3245:   Calling sequence of `func`:
3246: . ts - the `TS` context

3248:   Level: intermediate

3250:   Note:
3251:   The function set by `TSSetPostEvaluate()` is called after the solution is evaluated, or after the step rollback.
3252:   Inside the `func` callback, the solution vector can be obtained with `TSGetSolution()`, and modified, if need be.
3253:   The time step can be obtained with `TSGetTimeStep()`, and the time at the start of the step - via `TSGetTime()`.
3254:   The potential changes to the solution vector introduced by event handling (`postevent()`) are not relevant for `TSSetPostEvaluate()`,
3255:   but are relevant for `TSSetPostStep()`, according to the function call scheme in `TSSolve()`, as shown below
3256: .vb
3257:   ...
3258:   Step()
3259:   PostEvaluate()
3260:   EventHandling()
3261:   step_rollback ? PostEvaluate() : PostStep()
3262:   ...
3263: .ve
3264:   where EventHandling() may result in one of the following three outcomes
3265: .vb
3266:   (1) | successful step | solution intact
3267:   (2) | successful step | solution modified by `postevent()`
3268:   (3) | step_rollback   | solution rolled back
3269: .ve

3271: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3272: @*/
3273: PetscErrorCode TSSetPostEvaluate(TS ts, PetscErrorCode (*func)(TS ts))
3274: {
3275:   PetscFunctionBegin;
3277:   ts->postevaluate = func;
3278:   PetscFunctionReturn(PETSC_SUCCESS);
3279: }

3281: /*@
3282:   TSPreStage - Runs the user-defined pre-stage function set using `TSSetPreStage()`

3284:   Collective

3286:   Input Parameters:
3287: + ts        - The `TS` context obtained from `TSCreate()`
3288: - stagetime - The absolute time of the current stage

3290:   Level: developer

3292:   Note:
3293:   `TSPreStage()` is typically used within time stepping implementations,
3294:   most users would not generally call this routine themselves.

3296: .seealso: [](ch_ts), `TS`, `TSPostStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3297: @*/
3298: PetscErrorCode TSPreStage(TS ts, PetscReal stagetime)
3299: {
3300:   PetscFunctionBegin;
3302:   if (ts->prestage) PetscCallBack("TS callback prestage", (*ts->prestage)(ts, stagetime));
3303:   PetscFunctionReturn(PETSC_SUCCESS);
3304: }

3306: /*@
3307:   TSPostStage - Runs the user-defined post-stage function set using `TSSetPostStage()`

3309:   Collective

3311:   Input Parameters:
3312: + ts         - The `TS` context obtained from `TSCreate()`
3313: . stagetime  - The absolute time of the current stage
3314: . stageindex - Stage number
3315: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3317:   Level: developer

3319:   Note:
3320:   `TSPostStage()` is typically used within time stepping implementations,
3321:   most users would not generally call this routine themselves.

3323: .seealso: [](ch_ts), `TS`, `TSPreStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3324: @*/
3325: PetscErrorCode TSPostStage(TS ts, PetscReal stagetime, PetscInt stageindex, Vec Y[])
3326: {
3327:   PetscFunctionBegin;
3329:   if (ts->poststage) PetscCallBack("TS callback poststage", (*ts->poststage)(ts, stagetime, stageindex, Y));
3330:   PetscFunctionReturn(PETSC_SUCCESS);
3331: }

3333: /*@
3334:   TSPostEvaluate - Runs the user-defined post-evaluate function set using `TSSetPostEvaluate()`

3336:   Collective

3338:   Input Parameter:
3339: . ts - The `TS` context obtained from `TSCreate()`

3341:   Level: developer

3343:   Note:
3344:   `TSPostEvaluate()` is typically used within time stepping implementations,
3345:   most users would not generally call this routine themselves.

3347: .seealso: [](ch_ts), `TS`, `TSSetPostEvaluate()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3348: @*/
3349: PetscErrorCode TSPostEvaluate(TS ts)
3350: {
3351:   PetscFunctionBegin;
3353:   if (ts->postevaluate) {
3354:     Vec              U;
3355:     PetscObjectState sprev, spost;

3357:     PetscCall(TSGetSolution(ts, &U));
3358:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3359:     PetscCallBack("TS callback postevaluate", (*ts->postevaluate)(ts));
3360:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3361:     if (sprev != spost) PetscCall(TSRestartStep(ts));
3362:   }
3363:   PetscFunctionReturn(PETSC_SUCCESS);
3364: }

3366: /*@C
3367:   TSSetPostStep - Sets the general-purpose function
3368:   called once at the end of each successful time step.

3370:   Logically Collective

3372:   Input Parameters:
3373: + ts   - The `TS` context obtained from `TSCreate()`
3374: - func - The function

3376:   Calling sequence of `func`:
3377: . ts - the `TS` context

3379:   Level: intermediate

3381:   Note:
3382:   The function set by `TSSetPostStep()` is called after each successful step. If the event handler locates an event at the
3383:   given step, and `postevent()` modifies the solution vector, the solution vector obtained by `TSGetSolution()` inside `func` will
3384:   contain the changes. To get the solution without these changes, use `TSSetPostEvaluate()` to set the appropriate callback.
3385:   The scheme of the relevant function calls in `TSSolve()` is shown below
3386: .vb
3387:   ...
3388:   Step()
3389:   PostEvaluate()
3390:   EventHandling()
3391:   step_rollback ? PostEvaluate() : PostStep()
3392:   ...
3393: .ve
3394:   where EventHandling() may result in one of the following three outcomes
3395: .vb
3396:   (1) | successful step | solution intact
3397:   (2) | successful step | solution modified by `postevent()`
3398:   (3) | step_rollback   | solution rolled back
3399: .ve

3401: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSRestartStep()`
3402: @*/
3403: PetscErrorCode TSSetPostStep(TS ts, PetscErrorCode (*func)(TS ts))
3404: {
3405:   PetscFunctionBegin;
3407:   ts->poststep = func;
3408:   PetscFunctionReturn(PETSC_SUCCESS);
3409: }

3411: /*@
3412:   TSPostStep - Runs the user-defined post-step function that was set with `TSSetPostStep()`

3414:   Collective

3416:   Input Parameter:
3417: . ts - The `TS` context obtained from `TSCreate()`

3419:   Note:
3420:   `TSPostStep()` is typically used within time stepping implementations,
3421:   so most users would not generally call this routine themselves.

3423:   Level: developer

3425: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSSetPostStep()`
3426: @*/
3427: PetscErrorCode TSPostStep(TS ts)
3428: {
3429:   PetscFunctionBegin;
3431:   if (ts->poststep) {
3432:     Vec              U;
3433:     PetscObjectId    idprev;
3434:     PetscBool        sameObject;
3435:     PetscObjectState sprev, spost;

3437:     PetscCall(TSGetSolution(ts, &U));
3438:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3439:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3440:     PetscCallBack("TS callback poststep", (*ts->poststep)(ts));
3441:     PetscCall(TSGetSolution(ts, &U));
3442:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3443:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3444:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3445:   }
3446:   PetscFunctionReturn(PETSC_SUCCESS);
3447: }

3449: /*@
3450:   TSInterpolate - Interpolate the solution computed during the previous step to an arbitrary location in the interval

3452:   Collective

3454:   Input Parameters:
3455: + ts - time stepping context
3456: - t  - time to interpolate to

3458:   Output Parameter:
3459: . U - state at given time

3461:   Level: intermediate

3463:   Developer Notes:
3464:   `TSInterpolate()` and the storing of previous steps/stages should be generalized to support delay differential equations and continuous adjoints.

3466: .seealso: [](ch_ts), `TS`, `TSSetExactFinalTime()`, `TSSolve()`
3467: @*/
3468: PetscErrorCode TSInterpolate(TS ts, PetscReal t, Vec U)
3469: {
3470:   PetscFunctionBegin;
3473:   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);
3474:   PetscUseTypeMethod(ts, interpolate, t, U);
3475:   PetscFunctionReturn(PETSC_SUCCESS);
3476: }

3478: /*@
3479:   TSStep - Steps one time step

3481:   Collective

3483:   Input Parameter:
3484: . ts - the `TS` context obtained from `TSCreate()`

3486:   Level: developer

3488:   Notes:
3489:   The public interface for the ODE/DAE solvers is `TSSolve()`, you should almost for sure be using that routine and not this routine.

3491:   The hook set using `TSSetPreStep()` is called before each attempt to take the step. In general, the time step size may
3492:   be changed due to adaptive error controller or solve failures. Note that steps may contain multiple stages.

3494:   This may over-step the final time provided in `TSSetMaxTime()` depending on the time-step used. `TSSolve()` interpolates to exactly the
3495:   time provided in `TSSetMaxTime()`. One can use `TSInterpolate()` to determine an interpolated solution within the final timestep.

3497: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSInterpolate()`
3498: @*/
3499: PetscErrorCode TSStep(TS ts)
3500: {
3501:   static PetscBool cite = PETSC_FALSE;
3502:   PetscReal        ptime;

3504:   PetscFunctionBegin;
3506:   PetscCall(PetscCitationsRegister("@article{tspaper,\n"
3507:                                    "  title         = {{PETSc/TS}: A Modern Scalable {DAE/ODE} Solver Library},\n"
3508:                                    "  author        = {Abhyankar, Shrirang and Brown, Jed and Constantinescu, Emil and Ghosh, Debojyoti and Smith, Barry F. and Zhang, Hong},\n"
3509:                                    "  journal       = {arXiv e-preprints},\n"
3510:                                    "  eprint        = {1806.01437},\n"
3511:                                    "  archivePrefix = {arXiv},\n"
3512:                                    "  year          = {2018}\n}\n",
3513:                                    &cite));
3514:   PetscCall(TSSetUp(ts));
3515:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));
3516:   if (ts->eval_times)
3517:     ts->eval_times->worktol = 0; /* In each step of TSSolve() 'eval_times->worktol' will be meaningfully defined (later) only once:
3518:                                                    in TSAdaptChoose() or TSEvent_dt_cap(), and then reused till the end of the step */

3520:   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>");
3521:   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()");
3522:   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");

3524:   if (!ts->vec_sol0) PetscCall(VecDuplicate(ts->vec_sol, &ts->vec_sol0));
3525:   PetscCall(VecCopy(ts->vec_sol, ts->vec_sol0));
3526:   ts->time_step0 = ts->time_step;

3528:   if (!ts->steps) ts->ptime_prev = ts->ptime;
3529:   ptime = ts->ptime;

3531:   ts->ptime_prev_rollback = ts->ptime_prev;
3532:   ts->reason              = TS_CONVERGED_ITERATING;

3534:   PetscCall(PetscLogEventBegin(TS_Step, ts, 0, 0, 0));
3535:   PetscUseTypeMethod(ts, step);
3536:   PetscCall(PetscLogEventEnd(TS_Step, ts, 0, 0, 0));

3538:   if (ts->reason >= 0) {
3539:     ts->ptime_prev = ptime;
3540:     ts->steps++;
3541:     ts->steprollback = PETSC_FALSE;
3542:     ts->steprestart  = PETSC_FALSE;
3543:     ts->stepresize   = PETSC_FALSE;
3544:   }

3546:   if (ts->reason < 0 && ts->errorifstepfailed) {
3547:     PetscCall(TSMonitorCancel(ts));
3548:     if (ts->usessnes && ts->snes) PetscCall(SNESMonitorCancel(ts->snes));
3549:     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]);
3550:     SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_NOT_CONVERGED, "TSStep has failed due to %s", TSConvergedReasons[ts->reason]);
3551:   }
3552:   PetscFunctionReturn(PETSC_SUCCESS);
3553: }

3555: /*@
3556:   TSEvaluateWLTE - Evaluate the weighted local truncation error norm
3557:   at the end of a time step with a given order of accuracy.

3559:   Collective

3561:   Input Parameters:
3562: + ts        - time stepping context
3563: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

3565:   Input/Output Parameter:
3566: . order - optional, desired order for the error evaluation or `PETSC_DECIDE`;
3567:            on output, the actual order of the error evaluation

3569:   Output Parameter:
3570: . wlte - the weighted local truncation error norm

3572:   Level: advanced

3574:   Note:
3575:   If the timestepper cannot evaluate the error in a particular step
3576:   (eg. in the first step or restart steps after event handling),
3577:   this routine returns wlte=-1.0 .

3579: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`, `TSErrorWeightedNorm()`
3580: @*/
3581: PetscErrorCode TSEvaluateWLTE(TS ts, NormType wnormtype, PetscInt *order, PetscReal *wlte)
3582: {
3583:   PetscFunctionBegin;
3587:   if (order) PetscAssertPointer(order, 3);
3589:   PetscAssertPointer(wlte, 4);
3590:   PetscCheck(wnormtype == NORM_2 || wnormtype == NORM_INFINITY, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No support for norm type %s", NormTypes[wnormtype]);
3591:   PetscUseTypeMethod(ts, evaluatewlte, wnormtype, order, wlte);
3592:   PetscFunctionReturn(PETSC_SUCCESS);
3593: }

3595: /*@
3596:   TSEvaluateStep - Evaluate the solution at the end of a time step with a given order of accuracy.

3598:   Collective

3600:   Input Parameters:
3601: + ts    - time stepping context
3602: . order - desired order of accuracy
3603: - done  - whether the step was evaluated at this order (pass `NULL` to generate an error if not available)

3605:   Output Parameter:
3606: . U - state at the end of the current step

3608:   Level: advanced

3610:   Notes:
3611:   This function cannot be called until all stages have been evaluated.

3613:   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.

3615: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`
3616: @*/
3617: PetscErrorCode TSEvaluateStep(TS ts, PetscInt order, Vec U, PetscBool *done)
3618: {
3619:   PetscFunctionBegin;
3623:   PetscUseTypeMethod(ts, evaluatestep, order, U, done);
3624:   PetscFunctionReturn(PETSC_SUCCESS);
3625: }

3627: /*@C
3628:   TSGetComputeInitialCondition - Get the function used to automatically compute an initial condition for the timestepping.

3630:   Not collective

3632:   Input Parameter:
3633: . ts - time stepping context

3635:   Output Parameter:
3636: . initCondition - The function which computes an initial condition

3638:   Calling sequence of `initCondition`:
3639: + ts - The timestepping context
3640: - u  - The input vector in which the initial condition is stored

3642:   Level: advanced

3644: .seealso: [](ch_ts), `TS`, `TSSetComputeInitialCondition()`, `TSComputeInitialCondition()`
3645: @*/
3646: PetscErrorCode TSGetComputeInitialCondition(TS ts, PetscErrorCode (**initCondition)(TS ts, Vec u))
3647: {
3648:   PetscFunctionBegin;
3650:   PetscAssertPointer(initCondition, 2);
3651:   *initCondition = ts->ops->initcondition;
3652:   PetscFunctionReturn(PETSC_SUCCESS);
3653: }

3655: /*@C
3656:   TSSetComputeInitialCondition - Set the function used to automatically compute an initial condition for the timestepping.

3658:   Logically collective

3660:   Input Parameters:
3661: + ts            - time stepping context
3662: - initCondition - The function which computes an initial condition

3664:   Calling sequence of `initCondition`:
3665: + ts - The timestepping context
3666: - e  - The input vector in which the initial condition is to be stored

3668:   Level: advanced

3670: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSComputeInitialCondition()`
3671: @*/
3672: PetscErrorCode TSSetComputeInitialCondition(TS ts, PetscErrorCode (*initCondition)(TS ts, Vec e))
3673: {
3674:   PetscFunctionBegin;
3677:   ts->ops->initcondition = initCondition;
3678:   PetscFunctionReturn(PETSC_SUCCESS);
3679: }

3681: /*@
3682:   TSComputeInitialCondition - Compute an initial condition for the timestepping using the function previously set with `TSSetComputeInitialCondition()`

3684:   Collective

3686:   Input Parameters:
3687: + ts - time stepping context
3688: - u  - The `Vec` to store the condition in which will be used in `TSSolve()`

3690:   Level: advanced

3692: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3693: @*/
3694: PetscErrorCode TSComputeInitialCondition(TS ts, Vec u)
3695: {
3696:   PetscFunctionBegin;
3699:   PetscTryTypeMethod(ts, initcondition, u);
3700:   PetscFunctionReturn(PETSC_SUCCESS);
3701: }

3703: /*@C
3704:   TSGetComputeExactError - Get the function used to automatically compute the exact error for the timestepping.

3706:   Not collective

3708:   Input Parameter:
3709: . ts - time stepping context

3711:   Output Parameter:
3712: . exactError - The function which computes the solution error

3714:   Calling sequence of `exactError`:
3715: + ts - The timestepping context
3716: . u  - The approximate solution vector
3717: - e  - The vector in which the error is stored

3719:   Level: advanced

3721: .seealso: [](ch_ts), `TS`, `TSComputeExactError()`
3722: @*/
3723: PetscErrorCode TSGetComputeExactError(TS ts, PetscErrorCode (**exactError)(TS ts, Vec u, Vec e))
3724: {
3725:   PetscFunctionBegin;
3727:   PetscAssertPointer(exactError, 2);
3728:   *exactError = ts->ops->exacterror;
3729:   PetscFunctionReturn(PETSC_SUCCESS);
3730: }

3732: /*@C
3733:   TSSetComputeExactError - Set the function used to automatically compute the exact error for the timestepping.

3735:   Logically collective

3737:   Input Parameters:
3738: + ts         - time stepping context
3739: - exactError - The function which computes the solution error

3741:   Calling sequence of `exactError`:
3742: + ts - The timestepping context
3743: . u  - The approximate solution vector
3744: - e  - The  vector in which the error is stored

3746:   Level: advanced

3748: .seealso: [](ch_ts), `TS`, `TSGetComputeExactError()`, `TSComputeExactError()`
3749: @*/
3750: PetscErrorCode TSSetComputeExactError(TS ts, PetscErrorCode (*exactError)(TS ts, Vec u, Vec e))
3751: {
3752:   PetscFunctionBegin;
3755:   ts->ops->exacterror = exactError;
3756:   PetscFunctionReturn(PETSC_SUCCESS);
3757: }

3759: /*@
3760:   TSComputeExactError - Compute the solution error for the timestepping using the function previously set with `TSSetComputeExactError()`

3762:   Collective

3764:   Input Parameters:
3765: + ts - time stepping context
3766: . u  - The approximate solution
3767: - e  - The `Vec` used to store the error

3769:   Level: advanced

3771: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3772: @*/
3773: PetscErrorCode TSComputeExactError(TS ts, Vec u, Vec e)
3774: {
3775:   PetscFunctionBegin;
3779:   PetscTryTypeMethod(ts, exacterror, u, e);
3780:   PetscFunctionReturn(PETSC_SUCCESS);
3781: }

3783: /*@C
3784:   TSSetResize - Sets the resize callbacks.

3786:   Logically Collective

3788:   Input Parameters:
3789: + ts       - The `TS` context obtained from `TSCreate()`
3790: . rollback - Whether a resize will restart the step
3791: . setup    - The setup function
3792: . transfer - The transfer function
3793: - ctx      - [optional] The user-defined context

3795:   Calling sequence of `setup`:
3796: + ts     - the `TS` context
3797: . step   - the current step
3798: . time   - the current time
3799: . state  - the current vector of state
3800: . resize - (output parameter) `PETSC_TRUE` if need resizing, `PETSC_FALSE` otherwise
3801: - ctx    - user defined context

3803:   Calling sequence of `transfer`:
3804: + ts      - the `TS` context
3805: . nv      - the number of vectors to be transferred
3806: . vecsin  - array of vectors to be transferred
3807: . vecsout - array of transferred vectors
3808: - ctx     - user defined context

3810:   Notes:
3811:   The `setup` function is called inside `TSSolve()` after `TSEventHandler()` or after `TSPostStep()`
3812:   depending on the `rollback` value: if `rollback` is true, then these callbacks behave as error indicators
3813:   and will flag the need to remesh and restart the current step. Otherwise, they will simply flag the solver
3814:   that the size of the discrete problem has changed.
3815:   In both cases, the solver will collect the needed vectors that will be
3816:   transferred from the old to the new sizes using the `transfer` callback. These vectors will include the
3817:   current solution vector, and other vectors needed by the specific solver used.
3818:   For example, `TSBDF` uses previous solutions vectors to solve for the next time step.
3819:   Other application specific objects associated with the solver, i.e. Jacobian matrices and `DM`,
3820:   will be automatically reset if the sizes are changed and they must be specified again by the user
3821:   inside the `transfer` function.
3822:   The input and output arrays passed to `transfer` are allocated by PETSc.
3823:   Vectors in `vecsout` must be created by the user.
3824:   Ownership of vectors in `vecsout` is transferred to PETSc.

3826:   Level: advanced

3828: .seealso: [](ch_ts), `TS`, `TSSetDM()`, `TSSetIJacobian()`, `TSSetRHSJacobian()`
3829: @*/
3830: PetscErrorCode TSSetResize(TS ts, PetscBool rollback, PetscErrorCode (*setup)(TS ts, PetscInt step, PetscReal time, Vec state, PetscBool *resize, void *ctx), PetscErrorCode (*transfer)(TS ts, PetscInt nv, Vec vecsin[], Vec vecsout[], void *ctx), void *ctx)
3831: {
3832:   PetscFunctionBegin;
3834:   ts->resizerollback = rollback;
3835:   ts->resizesetup    = setup;
3836:   ts->resizetransfer = transfer;
3837:   ts->resizectx      = ctx;
3838:   PetscFunctionReturn(PETSC_SUCCESS);
3839: }

3841: /*
3842:   TSResizeRegisterOrRetrieve - Register or import vectors transferred with `TSResize()`.

3844:   Collective

3846:   Input Parameters:
3847: + ts   - The `TS` context obtained from `TSCreate()`
3848: - 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.

3850:   Level: developer

3852:   Note:
3853:   `TSResizeRegisterOrRetrieve()` is declared PETSC_INTERN since it is
3854:    used within time stepping implementations,
3855:    so most users would not generally call this routine themselves.

3857: .seealso: [](ch_ts), `TS`, `TSSetResize()`
3858: @*/
3859: static PetscErrorCode TSResizeRegisterOrRetrieve(TS ts, PetscBool flg)
3860: {
3861:   PetscFunctionBegin;
3863:   PetscTryTypeMethod(ts, resizeregister, flg);
3864:   /* PetscTryTypeMethod(adapt, resizeregister, flg); */
3865:   PetscFunctionReturn(PETSC_SUCCESS);
3866: }

3868: static PetscErrorCode TSResizeReset(TS ts)
3869: {
3870:   PetscFunctionBegin;
3872:   PetscCall(PetscObjectListDestroy(&ts->resizetransferobjs));
3873:   PetscFunctionReturn(PETSC_SUCCESS);
3874: }

3876: static PetscErrorCode TSResizeTransferVecs(TS ts, PetscInt cnt, Vec vecsin[], Vec vecsout[])
3877: {
3878:   PetscFunctionBegin;
3881:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPush(vecsin[i]));
3882:   if (ts->resizetransfer) {
3883:     PetscCall(PetscInfo(ts, "Transferring %" PetscInt_FMT " vectors\n", cnt));
3884:     PetscCallBack("TS callback resize transfer", (*ts->resizetransfer)(ts, cnt, vecsin, vecsout, ts->resizectx));
3885:   }
3886:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPop(vecsin[i]));
3887:   PetscFunctionReturn(PETSC_SUCCESS);
3888: }

3890: /*@C
3891:   TSResizeRegisterVec - Register a vector to be transferred with `TSResize()`.

3893:   Collective

3895:   Input Parameters:
3896: + ts   - The `TS` context obtained from `TSCreate()`
3897: . name - A string identifying the vector
3898: - vec  - The vector

3900:   Level: developer

3902:   Note:
3903:   `TSResizeRegisterVec()` is typically used within time stepping implementations,
3904:   so most users would not generally call this routine themselves.

3906: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRetrieveVec()`
3907: @*/
3908: PetscErrorCode TSResizeRegisterVec(TS ts, const char name[], Vec vec)
3909: {
3910:   PetscFunctionBegin;
3912:   PetscAssertPointer(name, 2);
3914:   PetscCall(PetscObjectListAdd(&ts->resizetransferobjs, name, (PetscObject)vec));
3915:   PetscFunctionReturn(PETSC_SUCCESS);
3916: }

3918: /*@C
3919:   TSResizeRetrieveVec - Retrieve a vector registered with `TSResizeRegisterVec()`.

3921:   Collective

3923:   Input Parameters:
3924: + ts   - The `TS` context obtained from `TSCreate()`
3925: . name - A string identifying the vector
3926: - vec  - The vector

3928:   Level: developer

3930:   Note:
3931:   `TSResizeRetrieveVec()` is typically used within time stepping implementations,
3932:   so most users would not generally call this routine themselves.

3934: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRegisterVec()`
3935: @*/
3936: PetscErrorCode TSResizeRetrieveVec(TS ts, const char name[], Vec *vec)
3937: {
3938:   PetscFunctionBegin;
3940:   PetscAssertPointer(name, 2);
3941:   PetscAssertPointer(vec, 3);
3942:   PetscCall(PetscObjectListFind(ts->resizetransferobjs, name, (PetscObject *)vec));
3943:   PetscFunctionReturn(PETSC_SUCCESS);
3944: }

3946: static PetscErrorCode TSResizeGetVecArray(TS ts, PetscInt *nv, const char **names[], Vec *vecs[])
3947: {
3948:   PetscInt        cnt;
3949:   PetscObjectList tmp;
3950:   Vec            *vecsin  = NULL;
3951:   const char    **namesin = NULL;

3953:   PetscFunctionBegin;
3954:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next)
3955:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) cnt++;
3956:   if (names) PetscCall(PetscMalloc1(cnt, &namesin));
3957:   if (vecs) PetscCall(PetscMalloc1(cnt, &vecsin));
3958:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next) {
3959:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) {
3960:       if (vecs) vecsin[cnt] = (Vec)tmp->obj;
3961:       if (names) namesin[cnt] = tmp->name;
3962:       cnt++;
3963:     }
3964:   }
3965:   if (nv) *nv = cnt;
3966:   if (names) *names = namesin;
3967:   if (vecs) *vecs = vecsin;
3968:   PetscFunctionReturn(PETSC_SUCCESS);
3969: }

3971: /*@
3972:   TSResize - Runs the user-defined transfer functions provided with `TSSetResize()`

3974:   Collective

3976:   Input Parameter:
3977: . ts - The `TS` context obtained from `TSCreate()`

3979:   Level: developer

3981:   Note:
3982:   `TSResize()` is typically used within time stepping implementations,
3983:   so most users would not generally call this routine themselves.

3985: .seealso: [](ch_ts), `TS`, `TSSetResize()`
3986: @*/
3987: PetscErrorCode TSResize(TS ts)
3988: {
3989:   PetscInt     nv      = 0;
3990:   const char **names   = NULL;
3991:   Vec         *vecsin  = NULL;
3992:   const char  *solname = "ts:vec_sol";

3994:   PetscFunctionBegin;
3996:   if (!ts->resizesetup) PetscFunctionReturn(PETSC_SUCCESS);
3997:   if (ts->resizesetup) {
3998:     PetscCall(VecLockReadPush(ts->vec_sol));
3999:     PetscCallBack("TS callback resize setup", (*ts->resizesetup)(ts, ts->steps, ts->ptime, ts->vec_sol, &ts->stepresize, ts->resizectx));
4000:     PetscCall(VecLockReadPop(ts->vec_sol));
4001:     if (ts->stepresize) {
4002:       if (ts->resizerollback) {
4003:         PetscCall(TSRollBack(ts));
4004:         ts->time_step = ts->time_step0;
4005:       }
4006:       PetscCall(TSResizeRegisterVec(ts, solname, ts->vec_sol));
4007:       PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_TRUE)); /* specific impls register their own objects */
4008:     }
4009:   }

4011:   PetscCall(TSResizeGetVecArray(ts, &nv, &names, &vecsin));
4012:   if (nv) {
4013:     Vec *vecsout, vecsol;

4015:     /* Reset internal objects */
4016:     PetscCall(TSReset(ts));

4018:     /* Transfer needed vectors (users can call SetJacobian, SetDM, etc. here) */
4019:     PetscCall(PetscCalloc1(nv, &vecsout));
4020:     PetscCall(TSResizeTransferVecs(ts, nv, vecsin, vecsout));
4021:     for (PetscInt i = 0; i < nv; i++) {
4022:       const char *name;
4023:       char       *oname;

4025:       PetscCall(PetscObjectGetName((PetscObject)vecsin[i], &name));
4026:       PetscCall(PetscStrallocpy(name, &oname));
4027:       PetscCall(TSResizeRegisterVec(ts, names[i], vecsout[i]));
4028:       if (vecsout[i]) PetscCall(PetscObjectSetName((PetscObject)vecsout[i], oname));
4029:       PetscCall(PetscFree(oname));
4030:       PetscCall(VecDestroy(&vecsout[i]));
4031:     }
4032:     PetscCall(PetscFree(vecsout));
4033:     PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_FALSE)); /* specific impls import the transferred objects */

4035:     PetscCall(TSResizeRetrieveVec(ts, solname, &vecsol));
4036:     if (vecsol) PetscCall(TSSetSolution(ts, vecsol));
4037:     PetscAssert(ts->vec_sol, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_NULL, "Missing TS solution");
4038:   }

4040:   PetscCall(PetscFree(names));
4041:   PetscCall(PetscFree(vecsin));
4042:   PetscCall(TSResizeReset(ts));
4043:   PetscFunctionReturn(PETSC_SUCCESS);
4044: }

4046: /*@
4047:   TSSolve - Steps the requested number of timesteps.

4049:   Collective

4051:   Input Parameters:
4052: + ts - the `TS` context obtained from `TSCreate()`
4053: - u  - the solution vector  (can be null if `TSSetSolution()` was used and `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`) was not used,
4054:        otherwise it must contain the initial conditions and will contain the solution at the final requested time

4056:   Level: beginner

4058:   Notes:
4059:   The final time returned by this function may be different from the time of the internally
4060:   held state accessible by `TSGetSolution()` and `TSGetTime()` because the method may have
4061:   stepped over the final time.

4063: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetSolution()`, `TSStep()`, `TSGetTime()`, `TSGetSolveTime()`
4064: @*/
4065: PetscErrorCode TSSolve(TS ts, Vec u)
4066: {
4067:   Vec solution;

4069:   PetscFunctionBegin;

4073:   PetscCall(TSSetExactFinalTimeDefault(ts));
4074:   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 */
4075:     if (!ts->vec_sol || u == ts->vec_sol) {
4076:       PetscCall(VecDuplicate(u, &solution));
4077:       PetscCall(TSSetSolution(ts, solution));
4078:       PetscCall(VecDestroy(&solution)); /* grant ownership */
4079:     }
4080:     PetscCall(VecCopy(u, ts->vec_sol));
4081:     PetscCheck(!ts->forward_solve, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Sensitivity analysis does not support the mode TS_EXACTFINALTIME_INTERPOLATE");
4082:   } else if (u) PetscCall(TSSetSolution(ts, u));
4083:   PetscCall(TSSetUp(ts));
4084:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));

4086:   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>");
4087:   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()");
4088:   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");
4089:   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");

4091:   if (ts->eval_times) {
4092:     if (!ts->eval_times->sol_vecs) PetscCall(VecDuplicateVecs(ts->vec_sol, ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
4093:     for (PetscInt i = 0; i < ts->eval_times->num_time_points; i++) {
4094:       PetscBool is_close = PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[i], ts->eval_times->reltol * ts->time_step + ts->eval_times->abstol, 0);
4095:       if (ts->ptime <= ts->eval_times->time_points[i] || is_close) {
4096:         ts->eval_times->time_point_idx = i;

4098:         PetscBool is_ptime_in_sol_times = PETSC_FALSE; // If current solution has already been saved, we should not save it again
4099:         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);
4100:         if (is_close && !is_ptime_in_sol_times) {
4101:           PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_idx]));
4102:           ts->eval_times->sol_times[ts->eval_times->sol_idx] = ts->ptime;
4103:           ts->eval_times->sol_idx++;
4104:           ts->eval_times->time_point_idx++;
4105:         }
4106:         break;
4107:       }
4108:     }
4109:   }

4111:   if (ts->forward_solve) PetscCall(TSForwardSetUp(ts));

4113:   /* reset number of steps only when the step is not restarted. ARKIMEX
4114:      restarts the step after an event. Resetting these counters in such case causes
4115:      TSTrajectory to incorrectly save the output files
4116:   */
4117:   /* reset time step and iteration counters */
4118:   if (!ts->steps) {
4119:     ts->ksp_its           = 0;
4120:     ts->snes_its          = 0;
4121:     ts->num_snes_failures = 0;
4122:     ts->reject            = 0;
4123:     ts->steprestart       = PETSC_TRUE;
4124:     ts->steprollback      = PETSC_FALSE;
4125:     ts->stepresize        = PETSC_FALSE;
4126:     ts->rhsjacobian.time  = PETSC_MIN_REAL;
4127:   }

4129:   /* make sure initial time step does not overshoot final time or the next point in evaluation times */
4130:   if (ts->exact_final_time == TS_EXACTFINALTIME_MATCHSTEP) {
4131:     PetscReal maxdt;
4132:     PetscReal dt = ts->time_step;

4134:     if (ts->eval_times) maxdt = ts->eval_times->time_points[ts->eval_times->time_point_idx] - ts->ptime;
4135:     else maxdt = ts->max_time - ts->ptime;
4136:     ts->time_step = dt >= maxdt ? maxdt : (PetscIsCloseAtTol(dt, maxdt, 10 * PETSC_MACHINE_EPSILON, 0) ? maxdt : dt);
4137:   }
4138:   ts->reason = TS_CONVERGED_ITERATING;

4140:   {
4141:     PetscViewer       viewer;
4142:     PetscViewerFormat format;
4143:     PetscBool         flg;
4144:     static PetscBool  incall = PETSC_FALSE;

4146:     if (!incall) {
4147:       /* Estimate the convergence rate of the time discretization */
4148:       PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)ts), ((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_estimate", &viewer, &format, &flg));
4149:       if (flg) {
4150:         PetscConvEst conv;
4151:         DM           dm;
4152:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4153:         PetscInt     Nf;
4154:         PetscBool    checkTemporal = PETSC_TRUE;

4156:         incall = PETSC_TRUE;
4157:         PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_temporal", &checkTemporal, &flg));
4158:         PetscCall(TSGetDM(ts, &dm));
4159:         PetscCall(DMGetNumFields(dm, &Nf));
4160:         PetscCall(PetscCalloc1(PetscMax(Nf, 1), &alpha));
4161:         PetscCall(PetscConvEstCreate(PetscObjectComm((PetscObject)ts), &conv));
4162:         PetscCall(PetscConvEstUseTS(conv, checkTemporal));
4163:         PetscCall(PetscConvEstSetSolver(conv, (PetscObject)ts));
4164:         PetscCall(PetscConvEstSetFromOptions(conv));
4165:         PetscCall(PetscConvEstSetUp(conv));
4166:         PetscCall(PetscConvEstGetConvRate(conv, alpha));
4167:         PetscCall(PetscViewerPushFormat(viewer, format));
4168:         PetscCall(PetscConvEstRateView(conv, alpha, viewer));
4169:         PetscCall(PetscViewerPopFormat(viewer));
4170:         PetscCall(PetscViewerDestroy(&viewer));
4171:         PetscCall(PetscConvEstDestroy(&conv));
4172:         PetscCall(PetscFree(alpha));
4173:         incall = PETSC_FALSE;
4174:       }
4175:     }
4176:   }

4178:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view_pre"));

4180:   if (ts->ops->solve) { /* This private interface is transitional and should be removed when all implementations are updated. */
4181:     PetscUseTypeMethod(ts, solve);
4182:     if (u) PetscCall(VecCopy(ts->vec_sol, u));
4183:     ts->solvetime = ts->ptime;
4184:     solution      = ts->vec_sol;
4185:   } else { /* Step the requested number of timesteps. */
4186:     if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4187:     else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;

4189:     if (!ts->steps) {
4190:       PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4191:       PetscCall(TSEventInitialize(ts->event, ts, ts->ptime, ts->vec_sol));
4192:     }

4194:     ts->start_step = ts->steps; // records starting step
4195:     while (!ts->reason) {
4196:       PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));
4197:       if (!ts->steprollback || (ts->stepresize && ts->resizerollback)) PetscCall(TSPreStep(ts));
4198:       PetscCall(TSStep(ts));
4199:       if (ts->testjacobian) PetscCall(TSRHSJacobianTest(ts, NULL));
4200:       if (ts->testjacobiantranspose) PetscCall(TSRHSJacobianTestTranspose(ts, NULL));
4201:       if (ts->quadraturets && ts->costintegralfwd) { /* Must evaluate the cost integral before event is handled. The cost integral value can also be rolled back. */
4202:         if (ts->reason >= 0) ts->steps--;            /* Revert the step number changed by TSStep() */
4203:         PetscCall(TSForwardCostIntegral(ts));
4204:         if (ts->reason >= 0) ts->steps++;
4205:       }
4206:       if (ts->forward_solve) {            /* compute forward sensitivities before event handling because postevent() may change RHS and jump conditions may have to be applied */
4207:         if (ts->reason >= 0) ts->steps--; /* Revert the step number changed by TSStep() */
4208:         PetscCall(TSForwardStep(ts));
4209:         if (ts->reason >= 0) ts->steps++;
4210:       }
4211:       PetscCall(TSPostEvaluate(ts));
4212:       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. */
4213:       if (ts->steprollback) PetscCall(TSPostEvaluate(ts));
4214:       if (!ts->steprollback && ts->resizerollback) PetscCall(TSResize(ts));
4215:       /* check convergence */
4216:       if (!ts->reason) {
4217:         if ((ts->steps - ts->start_step) >= ts->run_steps) ts->reason = TS_CONVERGED_ITS;
4218:         else if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4219:         else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;
4220:       }
4221:       if (!ts->steprollback) {
4222:         PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4223:         PetscCall(TSPostStep(ts));
4224:         if (!ts->resizerollback) PetscCall(TSResize(ts));

4226:         if (ts->eval_times && ts->eval_times->time_point_idx < ts->eval_times->num_time_points && ts->reason >= 0) {
4227:           PetscCheck(ts->eval_times->worktol > 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_PLIB, "Unexpected state !(eval_times->worktol > 0) in TSSolve()");
4228:           if (PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[ts->eval_times->time_point_idx], ts->eval_times->worktol, 0)) {
4229:             ts->eval_times->sol_times[ts->eval_times->sol_idx] = ts->ptime;
4230:             PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_idx]));
4231:             ts->eval_times->sol_idx++;
4232:             ts->eval_times->time_point_idx++;
4233:           }
4234:         }
4235:       }
4236:     }
4237:     PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));

4239:     if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE && ts->ptime > ts->max_time) {
4240:       if (!u) u = ts->vec_sol;
4241:       PetscCall(TSInterpolate(ts, ts->max_time, u));
4242:       ts->solvetime = ts->max_time;
4243:       solution      = u;
4244:       PetscCall(TSMonitor(ts, -1, ts->solvetime, solution));
4245:     } else {
4246:       if (u) PetscCall(VecCopy(ts->vec_sol, u));
4247:       ts->solvetime = ts->ptime;
4248:       solution      = ts->vec_sol;
4249:     }
4250:   }

4252:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view"));
4253:   PetscCall(VecViewFromOptions(solution, (PetscObject)ts, "-ts_view_solution"));
4254:   PetscCall(PetscObjectSAWsBlock((PetscObject)ts));
4255:   if (ts->adjoint_solve) PetscCall(TSAdjointSolve(ts));
4256:   PetscFunctionReturn(PETSC_SUCCESS);
4257: }

4259: /*@
4260:   TSGetTime - Gets the time of the most recently completed step.

4262:   Not Collective

4264:   Input Parameter:
4265: . ts - the `TS` context obtained from `TSCreate()`

4267:   Output Parameter:
4268: . t - the current time. This time may not corresponds to the final time set with `TSSetMaxTime()`, use `TSGetSolveTime()`.

4270:   Level: beginner

4272:   Note:
4273:   When called during time step evaluation (e.g. during residual evaluation or via hooks set using `TSSetPreStep()`,
4274:   `TSSetPreStage()`, `TSSetPostStage()`, or `TSSetPostStep()`), the time is the time at the start of the step being evaluated.

4276: .seealso: [](ch_ts), `TS`, `TSGetSolveTime()`, `TSSetTime()`, `TSGetTimeStep()`, `TSGetStepNumber()`
4277: @*/
4278: PetscErrorCode TSGetTime(TS ts, PetscReal *t)
4279: {
4280:   PetscFunctionBegin;
4282:   PetscAssertPointer(t, 2);
4283:   *t = ts->ptime;
4284:   PetscFunctionReturn(PETSC_SUCCESS);
4285: }

4287: /*@
4288:   TSGetPrevTime - Gets the starting time of the previously completed step.

4290:   Not Collective

4292:   Input Parameter:
4293: . ts - the `TS` context obtained from `TSCreate()`

4295:   Output Parameter:
4296: . t - the previous time

4298:   Level: beginner

4300: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetTimeStep()`
4301: @*/
4302: PetscErrorCode TSGetPrevTime(TS ts, PetscReal *t)
4303: {
4304:   PetscFunctionBegin;
4306:   PetscAssertPointer(t, 2);
4307:   *t = ts->ptime_prev;
4308:   PetscFunctionReturn(PETSC_SUCCESS);
4309: }

4311: /*@
4312:   TSSetTime - Allows one to reset the time.

4314:   Logically Collective

4316:   Input Parameters:
4317: + ts - the `TS` context obtained from `TSCreate()`
4318: - t  - the time

4320:   Level: intermediate

4322: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSSetMaxSteps()`
4323: @*/
4324: PetscErrorCode TSSetTime(TS ts, PetscReal t)
4325: {
4326:   PetscFunctionBegin;
4329:   ts->ptime = t;
4330:   PetscFunctionReturn(PETSC_SUCCESS);
4331: }

4333: /*@
4334:   TSSetOptionsPrefix - Sets the prefix used for searching for all
4335:   TS options in the database.

4337:   Logically Collective

4339:   Input Parameters:
4340: + ts     - The `TS` context
4341: - prefix - The prefix to prepend to all option names

4343:   Level: advanced

4345:   Note:
4346:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4347:   The first character of all runtime options is AUTOMATICALLY the
4348:   hyphen.

4350: .seealso: [](ch_ts), `TS`, `TSSetFromOptions()`, `TSAppendOptionsPrefix()`
4351: @*/
4352: PetscErrorCode TSSetOptionsPrefix(TS ts, const char prefix[])
4353: {
4354:   SNES snes;

4356:   PetscFunctionBegin;
4358:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)ts, prefix));
4359:   PetscCall(TSGetSNES(ts, &snes));
4360:   PetscCall(SNESSetOptionsPrefix(snes, prefix));
4361:   PetscFunctionReturn(PETSC_SUCCESS);
4362: }

4364: /*@
4365:   TSAppendOptionsPrefix - Appends to the prefix used for searching for all
4366:   TS options in the database.

4368:   Logically Collective

4370:   Input Parameters:
4371: + ts     - The `TS` context
4372: - prefix - The prefix to prepend to all option names

4374:   Level: advanced

4376:   Note:
4377:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4378:   The first character of all runtime options is AUTOMATICALLY the
4379:   hyphen.

4381: .seealso: [](ch_ts), `TS`, `TSGetOptionsPrefix()`, `TSSetOptionsPrefix()`, `TSSetFromOptions()`
4382: @*/
4383: PetscErrorCode TSAppendOptionsPrefix(TS ts, const char prefix[])
4384: {
4385:   SNES snes;

4387:   PetscFunctionBegin;
4389:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)ts, prefix));
4390:   PetscCall(TSGetSNES(ts, &snes));
4391:   PetscCall(SNESAppendOptionsPrefix(snes, prefix));
4392:   PetscFunctionReturn(PETSC_SUCCESS);
4393: }

4395: /*@
4396:   TSGetOptionsPrefix - Sets the prefix used for searching for all
4397:   `TS` options in the database.

4399:   Not Collective

4401:   Input Parameter:
4402: . ts - The `TS` context

4404:   Output Parameter:
4405: . prefix - A pointer to the prefix string used

4407:   Level: intermediate

4409: .seealso: [](ch_ts), `TS`, `TSAppendOptionsPrefix()`, `TSSetFromOptions()`
4410: @*/
4411: PetscErrorCode TSGetOptionsPrefix(TS ts, const char *prefix[])
4412: {
4413:   PetscFunctionBegin;
4415:   PetscAssertPointer(prefix, 2);
4416:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ts, prefix));
4417:   PetscFunctionReturn(PETSC_SUCCESS);
4418: }

4420: /*@C
4421:   TSGetRHSJacobian - Returns the Jacobian J at the present timestep.

4423:   Not Collective, but parallel objects are returned if ts is parallel

4425:   Input Parameter:
4426: . ts - The `TS` context obtained from `TSCreate()`

4428:   Output Parameters:
4429: + Amat - The (approximate) Jacobian J of G, where U_t = G(U,t)  (or `NULL`)
4430: . Pmat - The matrix from which the preconditioner is constructed, usually the same as `Amat`  (or `NULL`)
4431: . func - Function to compute the Jacobian of the RHS  (or `NULL`)
4432: - ctx  - User-defined context for Jacobian evaluation routine  (or `NULL`)

4434:   Level: intermediate

4436:   Note:
4437:   You can pass in `NULL` for any return argument you do not need.

4439: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`

4441: @*/
4442: PetscErrorCode TSGetRHSJacobian(TS ts, Mat *Amat, Mat *Pmat, TSRHSJacobianFn **func, void **ctx)
4443: {
4444:   DM dm;

4446:   PetscFunctionBegin;
4447:   if (Amat || Pmat) {
4448:     SNES snes;
4449:     PetscCall(TSGetSNES(ts, &snes));
4450:     PetscCall(SNESSetUpMatrices(snes));
4451:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4452:   }
4453:   PetscCall(TSGetDM(ts, &dm));
4454:   PetscCall(DMTSGetRHSJacobian(dm, func, ctx));
4455:   PetscFunctionReturn(PETSC_SUCCESS);
4456: }

4458: /*@C
4459:   TSGetIJacobian - Returns the implicit Jacobian at the present timestep.

4461:   Not Collective, but parallel objects are returned if ts is parallel

4463:   Input Parameter:
4464: . ts - The `TS` context obtained from `TSCreate()`

4466:   Output Parameters:
4467: + Amat - The (approximate) Jacobian of F(t,U,U_t)
4468: . Pmat - The matrix from which the preconditioner is constructed, often the same as `Amat`
4469: . f    - The function to compute the matrices
4470: - ctx  - User-defined context for Jacobian evaluation routine

4472:   Level: advanced

4474:   Note:
4475:   You can pass in `NULL` for any return argument you do not need.

4477: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetRHSJacobian()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`
4478: @*/
4479: PetscErrorCode TSGetIJacobian(TS ts, Mat *Amat, Mat *Pmat, TSIJacobianFn **f, void **ctx)
4480: {
4481:   DM dm;

4483:   PetscFunctionBegin;
4484:   if (Amat || Pmat) {
4485:     SNES snes;
4486:     PetscCall(TSGetSNES(ts, &snes));
4487:     PetscCall(SNESSetUpMatrices(snes));
4488:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4489:   }
4490:   PetscCall(TSGetDM(ts, &dm));
4491:   PetscCall(DMTSGetIJacobian(dm, f, ctx));
4492:   PetscFunctionReturn(PETSC_SUCCESS);
4493: }

4495: #include <petsc/private/dmimpl.h>
4496: /*@
4497:   TSSetDM - Sets the `DM` that may be used by some nonlinear solvers or preconditioners under the `TS`

4499:   Logically Collective

4501:   Input Parameters:
4502: + ts - the `TS` integrator object
4503: - dm - the dm, cannot be `NULL`

4505:   Level: intermediate

4507:   Notes:
4508:   A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
4509:   even when not using interfaces like `DMTSSetIFunction()`.  Use `DMClone()` to get a distinct `DM` when solving
4510:   different problems using the same function space.

4512: .seealso: [](ch_ts), `TS`, `DM`, `TSGetDM()`, `SNESSetDM()`, `SNESGetDM()`
4513: @*/
4514: PetscErrorCode TSSetDM(TS ts, DM dm)
4515: {
4516:   SNES snes;
4517:   DMTS tsdm;

4519:   PetscFunctionBegin;
4522:   PetscCall(PetscObjectReference((PetscObject)dm));
4523:   if (ts->dm) { /* Move the DMTS context over to the new DM unless the new DM already has one */
4524:     if (ts->dm->dmts && !dm->dmts) {
4525:       PetscCall(DMCopyDMTS(ts->dm, dm));
4526:       PetscCall(DMGetDMTS(ts->dm, &tsdm));
4527:       /* Grant write privileges to the replacement DM */
4528:       if (tsdm->originaldm == ts->dm) tsdm->originaldm = dm;
4529:     }
4530:     PetscCall(DMDestroy(&ts->dm));
4531:   }
4532:   ts->dm = dm;

4534:   PetscCall(TSGetSNES(ts, &snes));
4535:   PetscCall(SNESSetDM(snes, dm));
4536:   PetscFunctionReturn(PETSC_SUCCESS);
4537: }

4539: /*@
4540:   TSGetDM - Gets the `DM` that may be used by some preconditioners

4542:   Not Collective

4544:   Input Parameter:
4545: . ts - the `TS`

4547:   Output Parameter:
4548: . dm - the `DM`

4550:   Level: intermediate

4552: .seealso: [](ch_ts), `TS`, `DM`, `TSSetDM()`, `SNESSetDM()`, `SNESGetDM()`
4553: @*/
4554: PetscErrorCode TSGetDM(TS ts, DM *dm)
4555: {
4556:   PetscFunctionBegin;
4558:   if (!ts->dm) {
4559:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)ts), &ts->dm));
4560:     if (ts->snes) PetscCall(SNESSetDM(ts->snes, ts->dm));
4561:   }
4562:   *dm = ts->dm;
4563:   PetscFunctionReturn(PETSC_SUCCESS);
4564: }

4566: /*@
4567:   SNESTSFormFunction - Function to evaluate nonlinear residual defined by an ODE solver algorithm implemented within `TS`

4569:   Logically Collective

4571:   Input Parameters:
4572: + snes - nonlinear solver
4573: . U    - the current state at which to evaluate the residual
4574: - ctx  - user context, must be a `TS`

4576:   Output Parameter:
4577: . F - the nonlinear residual

4579:   Level: developer

4581:   Note:
4582:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.
4583:   It is most frequently passed to `MatFDColoringSetFunction()`.

4585: .seealso: [](ch_ts), `SNESSetFunction()`, `MatFDColoringSetFunction()`
4586: @*/
4587: PetscErrorCode SNESTSFormFunction(SNES snes, Vec U, Vec F, void *ctx)
4588: {
4589:   TS ts = (TS)ctx;

4591:   PetscFunctionBegin;
4596:   PetscCheck(ts->ops->snesfunction, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesfunction for TS of type %s", ((PetscObject)ts)->type_name);
4597:   PetscCall((*ts->ops->snesfunction)(snes, U, F, ts));
4598:   PetscFunctionReturn(PETSC_SUCCESS);
4599: }

4601: /*@
4602:   SNESTSFormJacobian - Function to evaluate the Jacobian defined by an ODE solver algorithm implemented within `TS`

4604:   Collective

4606:   Input Parameters:
4607: + snes - nonlinear solver
4608: . U    - the current state at which to evaluate the residual
4609: - ctx  - user context, must be a `TS`

4611:   Output Parameters:
4612: + A - the Jacobian
4613: - B - the matrix used to construct the preconditioner (often the same as `A`)

4615:   Level: developer

4617:   Note:
4618:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.

4620: .seealso: [](ch_ts), `SNESSetJacobian()`
4621: @*/
4622: PetscErrorCode SNESTSFormJacobian(SNES snes, Vec U, Mat A, Mat B, void *ctx)
4623: {
4624:   TS ts = (TS)ctx;

4626:   PetscFunctionBegin;
4632:   PetscCheck(ts->ops->snesjacobian, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesjacobian for TS of type %s", ((PetscObject)ts)->type_name);
4633:   PetscCall((*ts->ops->snesjacobian)(snes, U, A, B, ts));
4634:   PetscFunctionReturn(PETSC_SUCCESS);
4635: }

4637: /*@C
4638:   TSComputeRHSFunctionLinear - Evaluate the right-hand side via the user-provided Jacobian, for linear problems Udot = A U only

4640:   Collective

4642:   Input Parameters:
4643: + ts  - time stepping context
4644: . t   - time at which to evaluate
4645: . U   - state at which to evaluate
4646: - ctx - context

4648:   Output Parameter:
4649: . F - right-hand side

4651:   Level: intermediate

4653:   Note:
4654:   This function is intended to be passed to `TSSetRHSFunction()` to evaluate the right-hand side for linear problems.
4655:   The matrix (and optionally the evaluation context) should be passed to `TSSetRHSJacobian()`.

4657: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
4658: @*/
4659: PetscErrorCode TSComputeRHSFunctionLinear(TS ts, PetscReal t, Vec U, Vec F, void *ctx)
4660: {
4661:   Mat Arhs, Brhs;

4663:   PetscFunctionBegin;
4664:   PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
4665:   /* undo the damage caused by shifting */
4666:   PetscCall(TSRecoverRHSJacobian(ts, Arhs, Brhs));
4667:   PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
4668:   PetscCall(MatMult(Arhs, U, F));
4669:   PetscFunctionReturn(PETSC_SUCCESS);
4670: }

4672: /*@C
4673:   TSComputeRHSJacobianConstant - Reuses a Jacobian that is time-independent.

4675:   Collective

4677:   Input Parameters:
4678: + ts  - time stepping context
4679: . t   - time at which to evaluate
4680: . U   - state at which to evaluate
4681: - ctx - context

4683:   Output Parameters:
4684: + A - Jacobian
4685: - B - matrix used to construct the preconditioner, often the same as `A`

4687:   Level: intermediate

4689:   Note:
4690:   This function is intended to be passed to `TSSetRHSJacobian()` to evaluate the Jacobian for linear time-independent problems.

4692: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSFunctionLinear()`
4693: @*/
4694: PetscErrorCode TSComputeRHSJacobianConstant(TS ts, PetscReal t, Vec U, Mat A, Mat B, void *ctx)
4695: {
4696:   PetscFunctionBegin;
4697:   PetscFunctionReturn(PETSC_SUCCESS);
4698: }

4700: /*@C
4701:   TSComputeIFunctionLinear - Evaluate the left hand side via the user-provided Jacobian, for linear problems only

4703:   Collective

4705:   Input Parameters:
4706: + ts   - time stepping context
4707: . t    - time at which to evaluate
4708: . U    - state at which to evaluate
4709: . Udot - time derivative of state vector
4710: - ctx  - context

4712:   Output Parameter:
4713: . F - left hand side

4715:   Level: intermediate

4717:   Notes:
4718:   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
4719:   user is required to write their own `TSComputeIFunction()`.
4720:   This function is intended to be passed to `TSSetIFunction()` to evaluate the left hand side for linear problems.
4721:   The matrix (and optionally the evaluation context) should be passed to `TSSetIJacobian()`.

4723:   Note that using this function is NOT equivalent to using `TSComputeRHSFunctionLinear()` since that solves Udot = A U

4725: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIJacobianConstant()`, `TSComputeRHSFunctionLinear()`
4726: @*/
4727: PetscErrorCode TSComputeIFunctionLinear(TS ts, PetscReal t, Vec U, Vec Udot, Vec F, void *ctx)
4728: {
4729:   Mat A, B;

4731:   PetscFunctionBegin;
4732:   PetscCall(TSGetIJacobian(ts, &A, &B, NULL, NULL));
4733:   PetscCall(TSComputeIJacobian(ts, t, U, Udot, 1.0, A, B, PETSC_TRUE));
4734:   PetscCall(MatMult(A, Udot, F));
4735:   PetscFunctionReturn(PETSC_SUCCESS);
4736: }

4738: /*@C
4739:   TSComputeIJacobianConstant - Reuses the matrix previously computed with the provided `TSIJacobianFn` for a semi-implicit DAE or ODE

4741:   Collective

4743:   Input Parameters:
4744: + ts    - time stepping context
4745: . t     - time at which to evaluate
4746: . U     - state at which to evaluate
4747: . Udot  - time derivative of state vector
4748: . shift - shift to apply
4749: - ctx   - context

4751:   Output Parameters:
4752: + A - pointer to operator
4753: - B - pointer to matrix from which the preconditioner is built (often `A`)

4755:   Level: advanced

4757:   Notes:
4758:   This function is intended to be passed to `TSSetIJacobian()` to evaluate the Jacobian for linear time-independent problems.

4760:   It is only appropriate for problems of the form

4762:   $$
4763:   M \dot{U} = F(U,t)
4764:   $$

4766:   where M is constant and F is non-stiff.  The user must pass M to `TSSetIJacobian()`.  The current implementation only
4767:   works with IMEX time integration methods such as `TSROSW` and `TSARKIMEX`, since there is no support for de-constructing
4768:   an implicit operator of the form

4770:   $$
4771:   shift*M + J
4772:   $$

4774:   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
4775:   a copy of M or reassemble it when requested.

4777: .seealso: [](ch_ts), `TS`, `TSROSW`, `TSARKIMEX`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIFunctionLinear()`
4778: @*/
4779: PetscErrorCode TSComputeIJacobianConstant(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, void *ctx)
4780: {
4781:   PetscFunctionBegin;
4782:   PetscCall(MatScale(A, shift / ts->ijacobian.shift));
4783:   ts->ijacobian.shift = shift;
4784:   PetscFunctionReturn(PETSC_SUCCESS);
4785: }

4787: /*@
4788:   TSGetEquationType - Gets the type of the equation that `TS` is solving.

4790:   Not Collective

4792:   Input Parameter:
4793: . ts - the `TS` context

4795:   Output Parameter:
4796: . equation_type - see `TSEquationType`

4798:   Level: beginner

4800: .seealso: [](ch_ts), `TS`, `TSSetEquationType()`, `TSEquationType`
4801: @*/
4802: PetscErrorCode TSGetEquationType(TS ts, TSEquationType *equation_type)
4803: {
4804:   PetscFunctionBegin;
4806:   PetscAssertPointer(equation_type, 2);
4807:   *equation_type = ts->equation_type;
4808:   PetscFunctionReturn(PETSC_SUCCESS);
4809: }

4811: /*@
4812:   TSSetEquationType - Sets the type of the equation that `TS` is solving.

4814:   Not Collective

4816:   Input Parameters:
4817: + ts            - the `TS` context
4818: - equation_type - see `TSEquationType`

4820:   Level: advanced

4822: .seealso: [](ch_ts), `TS`, `TSGetEquationType()`, `TSEquationType`
4823: @*/
4824: PetscErrorCode TSSetEquationType(TS ts, TSEquationType equation_type)
4825: {
4826:   PetscFunctionBegin;
4828:   ts->equation_type = equation_type;
4829:   PetscFunctionReturn(PETSC_SUCCESS);
4830: }

4832: /*@
4833:   TSGetConvergedReason - Gets the reason the `TS` iteration was stopped.

4835:   Not Collective

4837:   Input Parameter:
4838: . ts - the `TS` context

4840:   Output Parameter:
4841: . reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4842:             manual pages for the individual convergence tests for complete lists

4844:   Level: beginner

4846:   Note:
4847:   Can only be called after the call to `TSSolve()` is complete.

4849: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4850: @*/
4851: PetscErrorCode TSGetConvergedReason(TS ts, TSConvergedReason *reason)
4852: {
4853:   PetscFunctionBegin;
4855:   PetscAssertPointer(reason, 2);
4856:   *reason = ts->reason;
4857:   PetscFunctionReturn(PETSC_SUCCESS);
4858: }

4860: /*@
4861:   TSSetConvergedReason - Sets the reason for handling the convergence of `TSSolve()`.

4863:   Logically Collective; reason must contain common value

4865:   Input Parameters:
4866: + ts     - the `TS` context
4867: - reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4868:             manual pages for the individual convergence tests for complete lists

4870:   Level: advanced

4872:   Note:
4873:   Can only be called while `TSSolve()` is active.

4875: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4876: @*/
4877: PetscErrorCode TSSetConvergedReason(TS ts, TSConvergedReason reason)
4878: {
4879:   PetscFunctionBegin;
4881:   ts->reason = reason;
4882:   PetscFunctionReturn(PETSC_SUCCESS);
4883: }

4885: /*@
4886:   TSGetSolveTime - Gets the time after a call to `TSSolve()`

4888:   Not Collective

4890:   Input Parameter:
4891: . ts - the `TS` context

4893:   Output Parameter:
4894: . ftime - the final time. This time corresponds to the final time set with `TSSetMaxTime()`

4896:   Level: beginner

4898:   Note:
4899:   Can only be called after the call to `TSSolve()` is complete.

4901: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4902: @*/
4903: PetscErrorCode TSGetSolveTime(TS ts, PetscReal *ftime)
4904: {
4905:   PetscFunctionBegin;
4907:   PetscAssertPointer(ftime, 2);
4908:   *ftime = ts->solvetime;
4909:   PetscFunctionReturn(PETSC_SUCCESS);
4910: }

4912: /*@
4913:   TSGetSNESIterations - Gets the total number of nonlinear iterations
4914:   used by the time integrator.

4916:   Not Collective

4918:   Input Parameter:
4919: . ts - `TS` context

4921:   Output Parameter:
4922: . nits - number of nonlinear iterations

4924:   Level: intermediate

4926:   Note:
4927:   This counter is reset to zero for each successive call to `TSSolve()`.

4929: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetKSPIterations()`
4930: @*/
4931: PetscErrorCode TSGetSNESIterations(TS ts, PetscInt *nits)
4932: {
4933:   PetscFunctionBegin;
4935:   PetscAssertPointer(nits, 2);
4936:   *nits = ts->snes_its;
4937:   PetscFunctionReturn(PETSC_SUCCESS);
4938: }

4940: /*@
4941:   TSGetKSPIterations - Gets the total number of linear iterations
4942:   used by the time integrator.

4944:   Not Collective

4946:   Input Parameter:
4947: . ts - `TS` context

4949:   Output Parameter:
4950: . lits - number of linear iterations

4952:   Level: intermediate

4954:   Note:
4955:   This counter is reset to zero for each successive call to `TSSolve()`.

4957: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`
4958: @*/
4959: PetscErrorCode TSGetKSPIterations(TS ts, PetscInt *lits)
4960: {
4961:   PetscFunctionBegin;
4963:   PetscAssertPointer(lits, 2);
4964:   *lits = ts->ksp_its;
4965:   PetscFunctionReturn(PETSC_SUCCESS);
4966: }

4968: /*@
4969:   TSGetStepRejections - Gets the total number of rejected steps.

4971:   Not Collective

4973:   Input Parameter:
4974: . ts - `TS` context

4976:   Output Parameter:
4977: . rejects - number of steps rejected

4979:   Level: intermediate

4981:   Note:
4982:   This counter is reset to zero for each successive call to `TSSolve()`.

4984: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetSNESFailures()`, `TSSetMaxSNESFailures()`, `TSSetErrorIfStepFails()`
4985: @*/
4986: PetscErrorCode TSGetStepRejections(TS ts, PetscInt *rejects)
4987: {
4988:   PetscFunctionBegin;
4990:   PetscAssertPointer(rejects, 2);
4991:   *rejects = ts->reject;
4992:   PetscFunctionReturn(PETSC_SUCCESS);
4993: }

4995: /*@
4996:   TSGetSNESFailures - Gets the total number of failed `SNES` solves in a `TS`

4998:   Not Collective

5000:   Input Parameter:
5001: . ts - `TS` context

5003:   Output Parameter:
5004: . fails - number of failed nonlinear solves

5006:   Level: intermediate

5008:   Note:
5009:   This counter is reset to zero for each successive call to `TSSolve()`.

5011: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSSetMaxSNESFailures()`
5012: @*/
5013: PetscErrorCode TSGetSNESFailures(TS ts, PetscInt *fails)
5014: {
5015:   PetscFunctionBegin;
5017:   PetscAssertPointer(fails, 2);
5018:   *fails = ts->num_snes_failures;
5019:   PetscFunctionReturn(PETSC_SUCCESS);
5020: }

5022: /*@
5023:   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`

5025:   Not Collective

5027:   Input Parameters:
5028: + ts      - `TS` context
5029: - rejects - maximum number of rejected steps, pass `PETSC_UNLIMITED` for unlimited

5031:   Options Database Key:
5032: . -ts_max_step_rejections - Maximum number of step rejections before a step fails

5034:   Level: intermediate

5036:   Developer Note:
5037:   The options database name is incorrect.

5039: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxSNESFailures()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSSetErrorIfStepFails()`,
5040:           `TSGetConvergedReason()`, `TSSolve()`, `TS_DIVERGED_STEP_REJECTED`
5041: @*/
5042: PetscErrorCode TSSetMaxStepRejections(TS ts, PetscInt rejects)
5043: {
5044:   PetscFunctionBegin;
5046:   if (rejects == PETSC_UNLIMITED || rejects == -1) {
5047:     ts->max_reject = PETSC_UNLIMITED;
5048:   } else {
5049:     PetscCheck(rejects >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of rejections");
5050:     ts->max_reject = rejects;
5051:   }
5052:   PetscFunctionReturn(PETSC_SUCCESS);
5053: }

5055: /*@
5056:   TSSetMaxSNESFailures - Sets the maximum number of failed `SNES` solves allowed before `TSSolve()` is ended with a `TSConvergedReason` of `TS_DIVERGED_NONLINEAR_SOLVE`

5058:   Not Collective

5060:   Input Parameters:
5061: + ts    - `TS` context
5062: - fails - maximum number of failed nonlinear solves, pass `PETSC_UNLIMITED` to allow any number of failures.

5064:   Options Database Key:
5065: . -ts_max_snes_failures - Maximum number of nonlinear solve failures

5067:   Level: intermediate

5069: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `SNESGetConvergedReason()`,
5070:           `TSGetConvergedReason()`, `TS_DIVERGED_NONLINEAR_SOLVE`, `TSConvergedReason`
5071: @*/
5072: PetscErrorCode TSSetMaxSNESFailures(TS ts, PetscInt fails)
5073: {
5074:   PetscFunctionBegin;
5076:   if (fails == PETSC_UNLIMITED || fails == -1) {
5077:     ts->max_snes_failures = PETSC_UNLIMITED;
5078:   } else {
5079:     PetscCheck(fails >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of failures");
5080:     ts->max_snes_failures = fails;
5081:   }
5082:   PetscFunctionReturn(PETSC_SUCCESS);
5083: }

5085: /*@
5086:   TSSetErrorIfStepFails - Immediately error if no step succeeds during `TSSolve()`

5088:   Not Collective

5090:   Input Parameters:
5091: + ts  - `TS` context
5092: - err - `PETSC_TRUE` to error if no step succeeds, `PETSC_FALSE` to return without failure

5094:   Options Database Key:
5095: . -ts_error_if_step_fails - Error if no step succeeds

5097:   Level: intermediate

5099: .seealso: [](ch_ts), `TS`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSGetConvergedReason()`
5100: @*/
5101: PetscErrorCode TSSetErrorIfStepFails(TS ts, PetscBool err)
5102: {
5103:   PetscFunctionBegin;
5105:   ts->errorifstepfailed = err;
5106:   PetscFunctionReturn(PETSC_SUCCESS);
5107: }

5109: /*@
5110:   TSGetAdapt - Get the adaptive controller context for the current method

5112:   Collective if controller has not yet been created

5114:   Input Parameter:
5115: . ts - time stepping context

5117:   Output Parameter:
5118: . adapt - adaptive controller

5120:   Level: intermediate

5122: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSAdaptSetType()`, `TSAdaptChoose()`
5123: @*/
5124: PetscErrorCode TSGetAdapt(TS ts, TSAdapt *adapt)
5125: {
5126:   PetscFunctionBegin;
5128:   PetscAssertPointer(adapt, 2);
5129:   if (!ts->adapt) {
5130:     PetscCall(TSAdaptCreate(PetscObjectComm((PetscObject)ts), &ts->adapt));
5131:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->adapt, (PetscObject)ts, 1));
5132:   }
5133:   *adapt = ts->adapt;
5134:   PetscFunctionReturn(PETSC_SUCCESS);
5135: }

5137: /*@
5138:   TSSetTolerances - Set tolerances for local truncation error when using an adaptive controller

5140:   Logically Collective

5142:   Input Parameters:
5143: + ts    - time integration context
5144: . atol  - scalar absolute tolerances
5145: . vatol - vector of absolute tolerances or `NULL`, used in preference to `atol` if present
5146: . rtol  - scalar relative tolerances
5147: - vrtol - vector of relative tolerances or `NULL`, used in preference to `rtol` if present

5149:   Options Database Keys:
5150: + -ts_rtol <rtol> - relative tolerance for local truncation error
5151: - -ts_atol <atol> - Absolute tolerance for local truncation error

5153:   Level: beginner

5155:   Notes:
5156:   `PETSC_CURRENT` or `PETSC_DETERMINE` may be used for `atol` or `rtol` to indicate the current value
5157:   or the default value from when the object's type was set.

5159:   With PETSc's implicit schemes for DAE problems, the calculation of the local truncation error
5160:   (LTE) includes both the differential and the algebraic variables. If one wants the LTE to be
5161:   computed only for the differential or the algebraic part then this can be done using the vector of
5162:   tolerances vatol. For example, by setting the tolerance vector with the desired tolerance for the
5163:   differential part and infinity for the algebraic part, the LTE calculation will include only the
5164:   differential variables.

5166:   Fortran Note:
5167:   Use `PETSC_CURRENT_INTEGER` or `PETSC_DETERMINE_INTEGER`.

5169: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSGetTolerances()`
5170: @*/
5171: PetscErrorCode TSSetTolerances(TS ts, PetscReal atol, Vec vatol, PetscReal rtol, Vec vrtol)
5172: {
5173:   PetscFunctionBegin;
5174:   if (atol == (PetscReal)PETSC_DETERMINE) {
5175:     ts->atol = ts->default_atol;
5176:   } else if (atol != (PetscReal)PETSC_CURRENT) {
5177:     PetscCheck(atol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Absolute tolerance %g must be non-negative", (double)atol);
5178:     ts->atol = atol;
5179:   }

5181:   if (vatol) {
5182:     PetscCall(PetscObjectReference((PetscObject)vatol));
5183:     PetscCall(VecDestroy(&ts->vatol));
5184:     ts->vatol = vatol;
5185:   }

5187:   if (rtol == (PetscReal)PETSC_DETERMINE) {
5188:     ts->rtol = ts->default_rtol;
5189:   } else if (rtol != (PetscReal)PETSC_CURRENT) {
5190:     PetscCheck(rtol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Relative tolerance %g must be non-negative", (double)rtol);
5191:     ts->rtol = rtol;
5192:   }

5194:   if (vrtol) {
5195:     PetscCall(PetscObjectReference((PetscObject)vrtol));
5196:     PetscCall(VecDestroy(&ts->vrtol));
5197:     ts->vrtol = vrtol;
5198:   }
5199:   PetscFunctionReturn(PETSC_SUCCESS);
5200: }

5202: /*@
5203:   TSGetTolerances - Get tolerances for local truncation error when using adaptive controller

5205:   Logically Collective

5207:   Input Parameter:
5208: . ts - time integration context

5210:   Output Parameters:
5211: + atol  - scalar absolute tolerances, `NULL` to ignore
5212: . vatol - vector of absolute tolerances, `NULL` to ignore
5213: . rtol  - scalar relative tolerances, `NULL` to ignore
5214: - vrtol - vector of relative tolerances, `NULL` to ignore

5216:   Level: beginner

5218: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSSetTolerances()`
5219: @*/
5220: PetscErrorCode TSGetTolerances(TS ts, PetscReal *atol, Vec *vatol, PetscReal *rtol, Vec *vrtol)
5221: {
5222:   PetscFunctionBegin;
5223:   if (atol) *atol = ts->atol;
5224:   if (vatol) *vatol = ts->vatol;
5225:   if (rtol) *rtol = ts->rtol;
5226:   if (vrtol) *vrtol = ts->vrtol;
5227:   PetscFunctionReturn(PETSC_SUCCESS);
5228: }

5230: /*@
5231:   TSErrorWeightedNorm - compute a weighted norm of the difference between two state vectors based on supplied absolute and relative tolerances

5233:   Collective

5235:   Input Parameters:
5236: + ts        - time stepping context
5237: . U         - state vector, usually ts->vec_sol
5238: . Y         - state vector to be compared to U
5239: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5241:   Output Parameters:
5242: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5243: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5244: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5246:   Options Database Key:
5247: . -ts_adapt_wnormtype <wnormtype> - 2, INFINITY

5249:   Level: developer

5251: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedENorm()`
5252: @*/
5253: PetscErrorCode TSErrorWeightedNorm(TS ts, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5254: {
5255:   PetscInt norma_loc, norm_loc, normr_loc;

5257:   PetscFunctionBegin;
5262:   PetscAssertPointer(norm, 5);
5263:   PetscAssertPointer(norma, 6);
5264:   PetscAssertPointer(normr, 7);
5265:   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));
5266:   if (wnormtype == NORM_2) {
5267:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5268:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5269:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5270:   }
5271:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5272:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5273:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5274:   PetscFunctionReturn(PETSC_SUCCESS);
5275: }

5277: /*@
5278:   TSErrorWeightedENorm - compute a weighted error norm based on supplied absolute and relative tolerances

5280:   Collective

5282:   Input Parameters:
5283: + ts        - time stepping context
5284: . E         - error vector
5285: . U         - state vector, usually ts->vec_sol
5286: . Y         - state vector, previous time step
5287: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5289:   Output Parameters:
5290: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5291: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5292: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5294:   Options Database Key:
5295: . -ts_adapt_wnormtype <wnormtype> - 2, INFINITY

5297:   Level: developer

5299: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedNorm()`
5300: @*/
5301: PetscErrorCode TSErrorWeightedENorm(TS ts, Vec E, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5302: {
5303:   PetscInt norma_loc, norm_loc, normr_loc;

5305:   PetscFunctionBegin;
5307:   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));
5308:   if (wnormtype == NORM_2) {
5309:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5310:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5311:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5312:   }
5313:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5314:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5315:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5316:   PetscFunctionReturn(PETSC_SUCCESS);
5317: }

5319: /*@
5320:   TSSetCFLTimeLocal - Set the local CFL constraint relative to forward Euler

5322:   Logically Collective

5324:   Input Parameters:
5325: + ts      - time stepping context
5326: - cfltime - maximum stable time step if using forward Euler (value can be different on each process)

5328:   Note:
5329:   After calling this function, the global CFL time can be obtained by calling TSGetCFLTime()

5331:   Level: intermediate

5333: .seealso: [](ch_ts), `TSGetCFLTime()`, `TSADAPTCFL`
5334: @*/
5335: PetscErrorCode TSSetCFLTimeLocal(TS ts, PetscReal cfltime)
5336: {
5337:   PetscFunctionBegin;
5339:   ts->cfltime_local = cfltime;
5340:   ts->cfltime       = -1.;
5341:   PetscFunctionReturn(PETSC_SUCCESS);
5342: }

5344: /*@
5345:   TSGetCFLTime - Get the maximum stable time step according to CFL criteria applied to forward Euler

5347:   Collective

5349:   Input Parameter:
5350: . ts - time stepping context

5352:   Output Parameter:
5353: . cfltime - maximum stable time step for forward Euler

5355:   Level: advanced

5357: .seealso: [](ch_ts), `TSSetCFLTimeLocal()`
5358: @*/
5359: PetscErrorCode TSGetCFLTime(TS ts, PetscReal *cfltime)
5360: {
5361:   PetscFunctionBegin;
5362:   if (ts->cfltime < 0) PetscCallMPI(MPIU_Allreduce(&ts->cfltime_local, &ts->cfltime, 1, MPIU_REAL, MPIU_MIN, PetscObjectComm((PetscObject)ts)));
5363:   *cfltime = ts->cfltime;
5364:   PetscFunctionReturn(PETSC_SUCCESS);
5365: }

5367: /*@
5368:   TSVISetVariableBounds - Sets the lower and upper bounds for the solution vector. xl <= x <= xu

5370:   Input Parameters:
5371: + ts - the `TS` context.
5372: . xl - lower bound.
5373: - xu - upper bound.

5375:   Level: advanced

5377:   Note:
5378:   If this routine is not called then the lower and upper bounds are set to
5379:   `PETSC_NINFINITY` and `PETSC_INFINITY` respectively during `SNESSetUp()`.

5381: .seealso: [](ch_ts), `TS`
5382: @*/
5383: PetscErrorCode TSVISetVariableBounds(TS ts, Vec xl, Vec xu)
5384: {
5385:   SNES snes;

5387:   PetscFunctionBegin;
5388:   PetscCall(TSGetSNES(ts, &snes));
5389:   PetscCall(SNESVISetVariableBounds(snes, xl, xu));
5390:   PetscFunctionReturn(PETSC_SUCCESS);
5391: }

5393: /*@
5394:   TSComputeLinearStability - computes the linear stability function at a point

5396:   Collective

5398:   Input Parameters:
5399: + ts - the `TS` context
5400: . xr - real part of input argument
5401: - xi - imaginary part of input argument

5403:   Output Parameters:
5404: + yr - real part of function value
5405: - yi - imaginary part of function value

5407:   Level: developer

5409: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSComputeIFunction()`
5410: @*/
5411: PetscErrorCode TSComputeLinearStability(TS ts, PetscReal xr, PetscReal xi, PetscReal *yr, PetscReal *yi)
5412: {
5413:   PetscFunctionBegin;
5415:   PetscUseTypeMethod(ts, linearstability, xr, xi, yr, yi);
5416:   PetscFunctionReturn(PETSC_SUCCESS);
5417: }

5419: /*@
5420:   TSRestartStep - Flags the solver to restart the next step

5422:   Collective

5424:   Input Parameter:
5425: . ts - the `TS` context obtained from `TSCreate()`

5427:   Level: advanced

5429:   Notes:
5430:   Multistep methods like `TSBDF` or Runge-Kutta methods with FSAL property require restarting the solver in the event of
5431:   discontinuities. These discontinuities may be introduced as a consequence of explicitly modifications to the solution
5432:   vector (which PETSc attempts to detect and handle) or problem coefficients (which PETSc is not able to detect). For
5433:   the sake of correctness and maximum safety, users are expected to call `TSRestart()` whenever they introduce
5434:   discontinuities in callback routines (e.g. prestep and poststep routines, or implicit/rhs function routines with
5435:   discontinuous source terms).

5437: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSSolve()`, `TSSetPreStep()`, `TSSetPostStep()`
5438: @*/
5439: PetscErrorCode TSRestartStep(TS ts)
5440: {
5441:   PetscFunctionBegin;
5443:   ts->steprestart = PETSC_TRUE;
5444:   PetscFunctionReturn(PETSC_SUCCESS);
5445: }

5447: /*@
5448:   TSRollBack - Rolls back one time step

5450:   Collective

5452:   Input Parameter:
5453: . ts - the `TS` context obtained from `TSCreate()`

5455:   Level: advanced

5457: .seealso: [](ch_ts), `TS`, `TSGetStepRollBack()`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSInterpolate()`
5458: @*/
5459: PetscErrorCode TSRollBack(TS ts)
5460: {
5461:   PetscFunctionBegin;
5463:   PetscCheck(!ts->steprollback, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "TSRollBack already called");
5464:   PetscTryTypeMethod(ts, rollback);
5465:   PetscCall(VecCopy(ts->vec_sol0, ts->vec_sol));
5466:   ts->time_step  = ts->ptime - ts->ptime_prev;
5467:   ts->ptime      = ts->ptime_prev;
5468:   ts->ptime_prev = ts->ptime_prev_rollback;
5469:   ts->steps--;
5470:   ts->steprollback = PETSC_TRUE;
5471:   PetscFunctionReturn(PETSC_SUCCESS);
5472: }

5474: /*@
5475:   TSGetStepRollBack - Get the internal flag indicating if you are rolling back a step

5477:   Not collective

5479:   Input Parameter:
5480: . ts - the `TS` context obtained from `TSCreate()`

5482:   Output Parameter:
5483: . flg - the rollback flag

5485:   Level: advanced

5487: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSRollBack()`
5488: @*/
5489: PetscErrorCode TSGetStepRollBack(TS ts, PetscBool *flg)
5490: {
5491:   PetscFunctionBegin;
5493:   PetscAssertPointer(flg, 2);
5494:   *flg = ts->steprollback;
5495:   PetscFunctionReturn(PETSC_SUCCESS);
5496: }

5498: /*@
5499:   TSGetStepResize - Get the internal flag indicating if the current step is after a resize.

5501:   Not collective

5503:   Input Parameter:
5504: . ts - the `TS` context obtained from `TSCreate()`

5506:   Output Parameter:
5507: . flg - the resize flag

5509:   Level: advanced

5511: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetResize()`
5512: @*/
5513: PetscErrorCode TSGetStepResize(TS ts, PetscBool *flg)
5514: {
5515:   PetscFunctionBegin;
5517:   PetscAssertPointer(flg, 2);
5518:   *flg = ts->stepresize;
5519:   PetscFunctionReturn(PETSC_SUCCESS);
5520: }

5522: /*@
5523:   TSGetStages - Get the number of stages and stage values

5525:   Input Parameter:
5526: . ts - the `TS` context obtained from `TSCreate()`

5528:   Output Parameters:
5529: + ns - the number of stages
5530: - Y  - the current stage vectors

5532:   Level: advanced

5534:   Note:
5535:   Both `ns` and `Y` can be `NULL`.

5537: .seealso: [](ch_ts), `TS`, `TSCreate()`
5538: @*/
5539: PetscErrorCode TSGetStages(TS ts, PetscInt *ns, Vec **Y)
5540: {
5541:   PetscFunctionBegin;
5543:   if (ns) PetscAssertPointer(ns, 2);
5544:   if (Y) PetscAssertPointer(Y, 3);
5545:   if (!ts->ops->getstages) {
5546:     if (ns) *ns = 0;
5547:     if (Y) *Y = NULL;
5548:   } else PetscUseTypeMethod(ts, getstages, ns, Y);
5549:   PetscFunctionReturn(PETSC_SUCCESS);
5550: }

5552: /*@C
5553:   TSComputeIJacobianDefaultColor - Computes the Jacobian using finite differences and coloring to exploit matrix sparsity.

5555:   Collective

5557:   Input Parameters:
5558: + ts    - the `TS` context
5559: . t     - current timestep
5560: . U     - state vector
5561: . Udot  - time derivative of state vector
5562: . shift - shift to apply, see note below
5563: - ctx   - an optional user context

5565:   Output Parameters:
5566: + J - Jacobian matrix (not altered in this routine)
5567: - B - newly computed Jacobian matrix to use with preconditioner (generally the same as `J`)

5569:   Level: intermediate

5571:   Notes:
5572:   If F(t,U,Udot)=0 is the DAE, the required Jacobian is

5574:   dF/dU + shift*dF/dUdot

5576:   Most users should not need to explicitly call this routine, as it
5577:   is used internally within the nonlinear solvers.

5579:   This will first try to get the coloring from the `DM`.  If the `DM` type has no coloring
5580:   routine, then it will try to get the coloring from the matrix.  This requires that the
5581:   matrix have nonzero entries precomputed.

5583: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
5584: @*/
5585: PetscErrorCode TSComputeIJacobianDefaultColor(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat J, Mat B, void *ctx)
5586: {
5587:   SNES          snes;
5588:   MatFDColoring color;
5589:   PetscBool     hascolor, matcolor = PETSC_FALSE;

5591:   PetscFunctionBegin;
5592:   PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_fd_color_use_mat", &matcolor, NULL));
5593:   PetscCall(PetscObjectQuery((PetscObject)B, "TSMatFDColoring", (PetscObject *)&color));
5594:   if (!color) {
5595:     DM         dm;
5596:     ISColoring iscoloring;

5598:     PetscCall(TSGetDM(ts, &dm));
5599:     PetscCall(DMHasColoring(dm, &hascolor));
5600:     if (hascolor && !matcolor) {
5601:       PetscCall(DMCreateColoring(dm, IS_COLORING_GLOBAL, &iscoloring));
5602:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5603:       PetscCall(MatFDColoringSetFunction(color, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
5604:       PetscCall(MatFDColoringSetFromOptions(color));
5605:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5606:       PetscCall(ISColoringDestroy(&iscoloring));
5607:     } else {
5608:       MatColoring mc;

5610:       PetscCall(MatColoringCreate(B, &mc));
5611:       PetscCall(MatColoringSetDistance(mc, 2));
5612:       PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
5613:       PetscCall(MatColoringSetFromOptions(mc));
5614:       PetscCall(MatColoringApply(mc, &iscoloring));
5615:       PetscCall(MatColoringDestroy(&mc));
5616:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5617:       PetscCall(MatFDColoringSetFunction(color, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
5618:       PetscCall(MatFDColoringSetFromOptions(color));
5619:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5620:       PetscCall(ISColoringDestroy(&iscoloring));
5621:     }
5622:     PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)color));
5623:     PetscCall(PetscObjectDereference((PetscObject)color));
5624:   }
5625:   PetscCall(TSGetSNES(ts, &snes));
5626:   PetscCall(MatFDColoringApply(B, color, U, snes));
5627:   if (J != B) {
5628:     PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
5629:     PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));
5630:   }
5631:   PetscFunctionReturn(PETSC_SUCCESS);
5632: }

5634: /*@C
5635:   TSSetFunctionDomainError - Set a function that tests if the current state vector is valid

5637:   Logically collective

5639:   Input Parameters:
5640: + ts   - the `TS` context
5641: - func - function called within `TSFunctionDomainError()`

5643:   Calling sequence of `func`:
5644: + ts     - the `TS` context
5645: . time   - the current time (of the stage)
5646: . state  - the state to check if it is valid
5647: - accept - (output parameter) `PETSC_FALSE` if the state is not acceptable, `PETSC_TRUE` if acceptable

5649:   Level: intermediate

5651:   Notes:
5652:   `accept` must be collectively specified.
5653:   If an implicit ODE solver is being used then, in addition to providing this routine, the
5654:   user's code should call `SNESSetFunctionDomainError()` when domain errors occur during
5655:   function evaluations where the functions are provided by `TSSetIFunction()` or `TSSetRHSFunction()`.
5656:   Use `TSGetSNES()` to obtain the `SNES` object

5658:   Developer Notes:
5659:   The naming of this function is inconsistent with the `SNESSetFunctionDomainError()`
5660:   since one takes a function pointer and the other does not.

5662: .seealso: [](ch_ts), `TSAdaptCheckStage()`, `TSFunctionDomainError()`, `SNESSetFunctionDomainError()`, `TSGetSNES()`
5663: @*/
5664: PetscErrorCode TSSetFunctionDomainError(TS ts, PetscErrorCode (*func)(TS ts, PetscReal time, Vec state, PetscBool *accept))
5665: {
5666:   PetscFunctionBegin;
5668:   ts->functiondomainerror = func;
5669:   PetscFunctionReturn(PETSC_SUCCESS);
5670: }

5672: /*@
5673:   TSFunctionDomainError - Checks if the current state is valid

5675:   Collective

5677:   Input Parameters:
5678: + ts        - the `TS` context
5679: . stagetime - time of the simulation
5680: - Y         - state vector to check.

5682:   Output Parameter:
5683: . accept - Set to `PETSC_FALSE` if the current state vector is valid.

5685:   Level: developer

5687:   Note:
5688:   This function is called by the `TS` integration routines and calls the user provided function (set with `TSSetFunctionDomainError()`)
5689:   to check if the current state is valid.

5691: .seealso: [](ch_ts), `TS`, `TSSetFunctionDomainError()`
5692: @*/
5693: PetscErrorCode TSFunctionDomainError(TS ts, PetscReal stagetime, Vec Y, PetscBool *accept)
5694: {
5695:   PetscFunctionBegin;
5699:   PetscAssertPointer(accept, 4);
5700:   *accept = PETSC_TRUE;
5701:   if (ts->functiondomainerror) PetscCall((*ts->functiondomainerror)(ts, stagetime, Y, accept));
5702:   PetscFunctionReturn(PETSC_SUCCESS);
5703: }

5705: /*@
5706:   TSClone - This function clones a time step `TS` object.

5708:   Collective

5710:   Input Parameter:
5711: . tsin - The input `TS`

5713:   Output Parameter:
5714: . tsout - The output `TS` (cloned)

5716:   Level: developer

5718:   Notes:
5719:   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.
5720:   It will likely be replaced in the future with a mechanism of switching methods on the fly.

5722:   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
5723: .vb
5724:  SNES snes_dup = NULL;
5725:  TSGetSNES(ts,&snes_dup);
5726:  TSSetSNES(ts,snes_dup);
5727: .ve

5729: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetType()`, `TSSetUp()`, `TSDestroy()`, `TSSetProblemType()`
5730: @*/
5731: PetscErrorCode TSClone(TS tsin, TS *tsout)
5732: {
5733:   TS     t;
5734:   SNES   snes_start;
5735:   DM     dm;
5736:   TSType type;

5738:   PetscFunctionBegin;
5739:   PetscAssertPointer(tsin, 1);
5740:   *tsout = NULL;

5742:   PetscCall(PetscHeaderCreate(t, TS_CLASSID, "TS", "Time stepping", "TS", PetscObjectComm((PetscObject)tsin), TSDestroy, TSView));

5744:   /* General TS description */
5745:   t->numbermonitors    = 0;
5746:   t->setupcalled       = PETSC_FALSE;
5747:   t->ksp_its           = 0;
5748:   t->snes_its          = 0;
5749:   t->nwork             = 0;
5750:   t->rhsjacobian.time  = PETSC_MIN_REAL;
5751:   t->rhsjacobian.scale = 1.;
5752:   t->ijacobian.shift   = 1.;

5754:   PetscCall(TSGetSNES(tsin, &snes_start));
5755:   PetscCall(TSSetSNES(t, snes_start));

5757:   PetscCall(TSGetDM(tsin, &dm));
5758:   PetscCall(TSSetDM(t, dm));

5760:   t->adapt = tsin->adapt;
5761:   PetscCall(PetscObjectReference((PetscObject)t->adapt));

5763:   t->trajectory = tsin->trajectory;
5764:   PetscCall(PetscObjectReference((PetscObject)t->trajectory));

5766:   t->event = tsin->event;
5767:   if (t->event) t->event->refct++;

5769:   t->problem_type      = tsin->problem_type;
5770:   t->ptime             = tsin->ptime;
5771:   t->ptime_prev        = tsin->ptime_prev;
5772:   t->time_step         = tsin->time_step;
5773:   t->max_time          = tsin->max_time;
5774:   t->steps             = tsin->steps;
5775:   t->max_steps         = tsin->max_steps;
5776:   t->equation_type     = tsin->equation_type;
5777:   t->atol              = tsin->atol;
5778:   t->rtol              = tsin->rtol;
5779:   t->max_snes_failures = tsin->max_snes_failures;
5780:   t->max_reject        = tsin->max_reject;
5781:   t->errorifstepfailed = tsin->errorifstepfailed;

5783:   PetscCall(TSGetType(tsin, &type));
5784:   PetscCall(TSSetType(t, type));

5786:   t->vec_sol = NULL;

5788:   t->cfltime          = tsin->cfltime;
5789:   t->cfltime_local    = tsin->cfltime_local;
5790:   t->exact_final_time = tsin->exact_final_time;

5792:   t->ops[0] = tsin->ops[0];

5794:   if (((PetscObject)tsin)->fortran_func_pointers) {
5795:     PetscInt i;
5796:     PetscCall(PetscMalloc((10) * sizeof(PetscFortranCallbackFn *), &((PetscObject)t)->fortran_func_pointers));
5797:     for (i = 0; i < 10; i++) ((PetscObject)t)->fortran_func_pointers[i] = ((PetscObject)tsin)->fortran_func_pointers[i];
5798:   }
5799:   *tsout = t;
5800:   PetscFunctionReturn(PETSC_SUCCESS);
5801: }

5803: static PetscErrorCode RHSWrapperFunction_TSRHSJacobianTest(void *ctx, Vec x, Vec y)
5804: {
5805:   TS ts = (TS)ctx;

5807:   PetscFunctionBegin;
5808:   PetscCall(TSComputeRHSFunction(ts, 0, x, y));
5809:   PetscFunctionReturn(PETSC_SUCCESS);
5810: }

5812: /*@
5813:   TSRHSJacobianTest - Compares the multiply routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5815:   Logically Collective

5817:   Input Parameter:
5818: . ts - the time stepping routine

5820:   Output Parameter:
5821: . flg - `PETSC_TRUE` if the multiply is likely correct

5823:   Options Database Key:
5824: . -ts_rhs_jacobian_test_mult -mat_shell_test_mult_view - run the test at each timestep of the integrator

5826:   Level: advanced

5828:   Note:
5829:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5831: .seealso: [](ch_ts), `TS`, `Mat`, `MATSHELL`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTestTranspose()`
5832: @*/
5833: PetscErrorCode TSRHSJacobianTest(TS ts, PetscBool *flg)
5834: {
5835:   Mat              J, B;
5836:   TSRHSJacobianFn *func;
5837:   void            *ctx;

5839:   PetscFunctionBegin;
5840:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5841:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5842:   PetscCall(MatShellTestMult(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5843:   PetscFunctionReturn(PETSC_SUCCESS);
5844: }

5846: /*@
5847:   TSRHSJacobianTestTranspose - Compares the multiply transpose routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5849:   Logically Collective

5851:   Input Parameter:
5852: . ts - the time stepping routine

5854:   Output Parameter:
5855: . flg - `PETSC_TRUE` if the multiply is likely correct

5857:   Options Database Key:
5858: . -ts_rhs_jacobian_test_mult_transpose -mat_shell_test_mult_transpose_view - run the test at each timestep of the integrator

5860:   Level: advanced

5862:   Notes:
5863:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5865: .seealso: [](ch_ts), `TS`, `Mat`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTest()`
5866: @*/
5867: PetscErrorCode TSRHSJacobianTestTranspose(TS ts, PetscBool *flg)
5868: {
5869:   Mat              J, B;
5870:   void            *ctx;
5871:   TSRHSJacobianFn *func;

5873:   PetscFunctionBegin;
5874:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5875:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5876:   PetscCall(MatShellTestMultTranspose(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5877:   PetscFunctionReturn(PETSC_SUCCESS);
5878: }

5880: /*@
5881:   TSSetUseSplitRHSFunction - Use the split RHSFunction when a multirate method is used.

5883:   Logically Collective

5885:   Input Parameters:
5886: + ts                   - timestepping context
5887: - use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5889:   Options Database Key:
5890: . -ts_use_splitrhsfunction - <true,false>

5892:   Level: intermediate

5894:   Note:
5895:   This is only for multirate methods

5897: .seealso: [](ch_ts), `TS`, `TSGetUseSplitRHSFunction()`
5898: @*/
5899: PetscErrorCode TSSetUseSplitRHSFunction(TS ts, PetscBool use_splitrhsfunction)
5900: {
5901:   PetscFunctionBegin;
5903:   ts->use_splitrhsfunction = use_splitrhsfunction;
5904:   PetscFunctionReturn(PETSC_SUCCESS);
5905: }

5907: /*@
5908:   TSGetUseSplitRHSFunction - Gets whether to use the split RHSFunction when a multirate method is used.

5910:   Not Collective

5912:   Input Parameter:
5913: . ts - timestepping context

5915:   Output Parameter:
5916: . use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5918:   Level: intermediate

5920: .seealso: [](ch_ts), `TS`, `TSSetUseSplitRHSFunction()`
5921: @*/
5922: PetscErrorCode TSGetUseSplitRHSFunction(TS ts, PetscBool *use_splitrhsfunction)
5923: {
5924:   PetscFunctionBegin;
5926:   *use_splitrhsfunction = ts->use_splitrhsfunction;
5927:   PetscFunctionReturn(PETSC_SUCCESS);
5928: }

5930: /*@
5931:   TSSetMatStructure - sets the relationship between the nonzero structure of the RHS Jacobian matrix to the IJacobian matrix.

5933:   Logically  Collective

5935:   Input Parameters:
5936: + ts  - the time-stepper
5937: - str - the structure (the default is `UNKNOWN_NONZERO_PATTERN`)

5939:   Level: intermediate

5941:   Note:
5942:   When the relationship between the nonzero structures is known and supplied the solution process can be much faster

5944: .seealso: [](ch_ts), `TS`, `MatAXPY()`, `MatStructure`
5945:  @*/
5946: PetscErrorCode TSSetMatStructure(TS ts, MatStructure str)
5947: {
5948:   PetscFunctionBegin;
5950:   ts->axpy_pattern = str;
5951:   PetscFunctionReturn(PETSC_SUCCESS);
5952: }

5954: /*@
5955:   TSSetEvaluationTimes - sets the evaluation points. The solution will be computed and stored for each time requested

5957:   Collective

5959:   Input Parameters:
5960: + ts          - the time-stepper
5961: . n           - number of the time points
5962: - time_points - array of the time points, must be increasing

5964:   Options Database Key:
5965: . -ts_eval_times <t0,...tn> - Sets the evaluation times

5967:   Level: intermediate

5969:   Notes:
5970:   The elements in `time_points` must be all increasing. They correspond to the intermediate points to be saved.

5972:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

5974:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using evaluation times may
5975:   pressure the memory system when using a large number of time points.

5977: .seealso: [](ch_ts), `TS`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`, `TSSetTimeSpan()`
5978:  @*/
5979: PetscErrorCode TSSetEvaluationTimes(TS ts, PetscInt n, PetscReal time_points[])
5980: {
5981:   PetscBool is_sorted;

5983:   PetscFunctionBegin;
5985:   if (ts->eval_times) { // Reset eval_times
5986:     ts->eval_times->sol_idx        = 0;
5987:     ts->eval_times->time_point_idx = 0;
5988:     if (n != ts->eval_times->num_time_points) {
5989:       PetscCall(PetscFree(ts->eval_times->time_points));
5990:       PetscCall(PetscFree(ts->eval_times->sol_times));
5991:       PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
5992:     } else {
5993:       PetscCall(PetscArrayzero(ts->eval_times->sol_times, n));
5994:       for (PetscInt i = 0; i < n; i++) PetscCall(VecZeroEntries(ts->eval_times->sol_vecs[i]));
5995:     }
5996:   } else { // Create/initialize eval_times
5997:     TSEvaluationTimes eval_times;
5998:     PetscCall(PetscNew(&eval_times));
5999:     PetscCall(PetscMalloc1(n, &eval_times->time_points));
6000:     PetscCall(PetscMalloc1(n, &eval_times->sol_times));
6001:     eval_times->reltol  = 1e-6;
6002:     eval_times->abstol  = 10 * PETSC_MACHINE_EPSILON;
6003:     eval_times->worktol = 0;
6004:     ts->eval_times      = eval_times;
6005:   }
6006:   ts->eval_times->num_time_points = n;
6007:   PetscCall(PetscSortedReal(n, time_points, &is_sorted));
6008:   PetscCheck(is_sorted, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "time_points array must be sorted");
6009:   PetscCall(PetscArraycpy(ts->eval_times->time_points, time_points, n));
6010:   // Note: ts->vec_sol not guaranteed to exist, so ts->eval_times->sol_vecs allocated at TSSolve time
6011:   PetscFunctionReturn(PETSC_SUCCESS);
6012: }

6014: /*@C
6015:   TSGetEvaluationTimes - gets the evaluation times set with `TSSetEvaluationTimes()`

6017:   Not Collective

6019:   Input Parameter:
6020: . ts - the time-stepper

6022:   Output Parameters:
6023: + n           - number of the time points
6024: - time_points - array of the time points

6026:   Level: beginner

6028:   Note:
6029:   The values obtained are valid until the `TS` object is destroyed.

6031:   Both `n` and `time_points` can be `NULL`.

6033:   Also used to see time points set by `TSSetTimeSpan()`.

6035: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationSolutions()`
6036:  @*/
6037: PetscErrorCode TSGetEvaluationTimes(TS ts, PetscInt *n, const PetscReal *time_points[])
6038: {
6039:   PetscFunctionBegin;
6041:   if (n) PetscAssertPointer(n, 2);
6042:   if (time_points) PetscAssertPointer(time_points, 3);
6043:   if (!ts->eval_times) {
6044:     if (n) *n = 0;
6045:     if (time_points) *time_points = NULL;
6046:   } else {
6047:     if (n) *n = ts->eval_times->num_time_points;
6048:     if (time_points) *time_points = ts->eval_times->time_points;
6049:   }
6050:   PetscFunctionReturn(PETSC_SUCCESS);
6051: }

6053: /*@C
6054:   TSGetEvaluationSolutions - Get the number of solutions and the solutions at the evaluation time points specified

6056:   Input Parameter:
6057: . ts - the `TS` context obtained from `TSCreate()`

6059:   Output Parameters:
6060: + nsol      - the number of solutions
6061: . sol_times - array of solution times corresponding to the solution vectors. See note below
6062: - Sols      - the solution vectors

6064:   Level: intermediate

6066:   Notes:
6067:   Both `nsol` and `Sols` can be `NULL`.

6069:   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()`.
6070:   For example, manipulating the step size, especially with a reduced precision, may cause `TS` to step over certain evaluation times.

6072:   Also used to see view solutions requested by `TSSetTimeSpan()`.

6074: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`
6075: @*/
6076: PetscErrorCode TSGetEvaluationSolutions(TS ts, PetscInt *nsol, const PetscReal *sol_times[], Vec *Sols[])
6077: {
6078:   PetscFunctionBegin;
6080:   if (nsol) PetscAssertPointer(nsol, 2);
6081:   if (sol_times) PetscAssertPointer(sol_times, 3);
6082:   if (Sols) PetscAssertPointer(Sols, 4);
6083:   if (!ts->eval_times) {
6084:     if (nsol) *nsol = 0;
6085:     if (sol_times) *sol_times = NULL;
6086:     if (Sols) *Sols = NULL;
6087:   } else {
6088:     if (nsol) *nsol = ts->eval_times->sol_idx;
6089:     if (sol_times) *sol_times = ts->eval_times->sol_times;
6090:     if (Sols) *Sols = ts->eval_times->sol_vecs;
6091:   }
6092:   PetscFunctionReturn(PETSC_SUCCESS);
6093: }

6095: /*@
6096:   TSSetTimeSpan - sets the time span. The solution will be computed and stored for each time requested in the span

6098:   Collective

6100:   Input Parameters:
6101: + ts         - the time-stepper
6102: . n          - number of the time points (>=2)
6103: - 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.

6105:   Options Database Key:
6106: . -ts_time_span <t0,...tf> - Sets the time span

6108:   Level: intermediate

6110:   Notes:
6111:   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.

6113:   The elements in `span_times` must be all increasing. They correspond to the intermediate points to be saved.

6115:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

6117:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using time span may
6118:   pressure the memory system when using a large number of span points.

6120: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`
6121:  @*/
6122: PetscErrorCode TSSetTimeSpan(TS ts, PetscInt n, PetscReal span_times[])
6123: {
6124:   PetscFunctionBegin;
6126:   PetscCheck(n >= 2, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Minimum time span size is 2 but %" PetscInt_FMT " is provided", n);
6127:   PetscCall(TSSetEvaluationTimes(ts, n, span_times));
6128:   PetscCall(TSSetTime(ts, span_times[0]));
6129:   PetscCall(TSSetMaxTime(ts, span_times[n - 1]));
6130:   PetscFunctionReturn(PETSC_SUCCESS);
6131: }

6133: /*@
6134:   TSPruneIJacobianColor - Remove nondiagonal zeros in the Jacobian matrix and update the `MatMFFD` coloring information.

6136:   Collective

6138:   Input Parameters:
6139: + ts - the `TS` context
6140: . J  - Jacobian matrix (not altered in this routine)
6141: - B  - newly computed Jacobian matrix to use with preconditioner

6143:   Level: intermediate

6145:   Notes:
6146:   This function improves the `MatFDColoring` performance when the Jacobian matrix was over-allocated or contains
6147:   many constant zeros entries, which is typically the case when the matrix is generated by a `DM`
6148:   and multiple fields are involved.

6150:   Users need to make sure that the Jacobian matrix is properly filled to reflect the sparsity
6151:   structure. For `MatFDColoring`, the values of nonzero entries are not important. So one can
6152:   usually call `TSComputeIJacobian()` with randomized input vectors to generate a dummy Jacobian.
6153:   `TSComputeIJacobian()` should be called before `TSSolve()` but after `TSSetUp()`.

6155: .seealso: [](ch_ts), `TS`, `MatFDColoring`, `TSComputeIJacobianDefaultColor()`, `MatEliminateZeros()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
6156: @*/
6157: PetscErrorCode TSPruneIJacobianColor(TS ts, Mat J, Mat B)
6158: {
6159:   MatColoring   mc            = NULL;
6160:   ISColoring    iscoloring    = NULL;
6161:   MatFDColoring matfdcoloring = NULL;

6163:   PetscFunctionBegin;
6164:   /* Generate new coloring after eliminating zeros in the matrix */
6165:   PetscCall(MatEliminateZeros(B, PETSC_TRUE));
6166:   PetscCall(MatColoringCreate(B, &mc));
6167:   PetscCall(MatColoringSetDistance(mc, 2));
6168:   PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
6169:   PetscCall(MatColoringSetFromOptions(mc));
6170:   PetscCall(MatColoringApply(mc, &iscoloring));
6171:   PetscCall(MatColoringDestroy(&mc));
6172:   /* Replace the old coloring with the new one */
6173:   PetscCall(MatFDColoringCreate(B, iscoloring, &matfdcoloring));
6174:   PetscCall(MatFDColoringSetFunction(matfdcoloring, (MatFDColoringFn *)SNESTSFormFunction, (void *)ts));
6175:   PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
6176:   PetscCall(MatFDColoringSetUp(B, iscoloring, matfdcoloring));
6177:   PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)matfdcoloring));
6178:   PetscCall(PetscObjectDereference((PetscObject)matfdcoloring));
6179:   PetscCall(ISColoringDestroy(&iscoloring));
6180:   PetscFunctionReturn(PETSC_SUCCESS);
6181: }