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 number of time-steps to take
 40: . -ts_init_time <time>                                               - initial time to start computation
 41: . -ts_final_time <time>                                              - final time to compute to (deprecated: use `-ts_max_time`)
 42: . -ts_dt <dt>                                                        - initial time step
 43: . -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
 44: . -ts_max_snes_failures <maxfailures>                                - Maximum number of nonlinear solve failures allowed
 45: . -ts_max_reject <maxrejects>                                        - Maximum number of step rejections before step fails
 46: . -ts_error_if_step_fails <true,false>                               - Error if no step succeeds
 47: . -ts_rtol <rtol>                                                    - relative tolerance for local truncation error
 48: . -ts_atol <atol>                                                    - Absolute tolerance for local truncation error
 49: . -ts_rhs_jacobian_test_mult -mat_shell_test_mult_view               - test the Jacobian at each iteration against finite difference with RHS function
 50: . -ts_rhs_jacobian_test_mult_transpose                               - test the Jacobian at each iteration against finite difference with RHS function
 51: . -ts_adjoint_solve <yes,no>                                         - After solving the ODE/DAE solve the adjoint problem (requires `-ts_save_trajectory`)
 52: . -ts_fd_color                                                       - Use finite differences with coloring to compute IJacobian
 53: . -ts_monitor                                                        - print information at each timestep
 54: . -ts_monitor_cancel                                                 - Cancel all monitors
 55: . -ts_monitor_lg_solution                                            - Monitor solution graphically
 56: . -ts_monitor_lg_error                                               - Monitor error graphically
 57: . -ts_monitor_error                                                  - Monitors norm of error
 58: . -ts_monitor_lg_timestep                                            - Monitor timestep size graphically
 59: . -ts_monitor_lg_timestep_log                                        - Monitor log timestep size graphically
 60: . -ts_monitor_lg_snes_iterations                                     - Monitor number nonlinear iterations for each timestep graphically
 61: . -ts_monitor_lg_ksp_iterations                                      - Monitor number nonlinear iterations for each timestep graphically
 62: . -ts_monitor_sp_eig                                                 - Monitor eigenvalues of linearized operator graphically
 63: . -ts_monitor_draw_solution                                          - Monitor solution graphically
 64: . -ts_monitor_draw_solution_phase  <xleft,yleft,xright,yright>       - Monitor solution graphically with phase diagram, requires problem with exactly 2 degrees of freedom
 65: . -ts_monitor_draw_error                                             - Monitor error graphically, requires use to have provided TSSetSolutionFunction()
 66: . -ts_monitor_solution [ascii binary draw][:filename][:viewerformat] - monitors the solution at each timestep
 67: . -ts_monitor_solution_interval <interval>                           - output once every interval (default=1) time steps. Use -1 to only output at the end of the simulation
 68: . -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)
 69: . -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
 70: - -ts_monitor_envelope                                               - determine maximum and minimum value of each component of the solution over the solution time

 72:   Level: beginner

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

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

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

 84: .seealso: [](ch_ts), `TS`, `TSGetType()`
 85: @*/
 86: PetscErrorCode TSSetFromOptions(TS ts)
 87: {
 88:   PetscBool              opt, flg, tflg;
 89:   char                   monfilename[PETSC_MAX_PATH_LEN];
 90:   PetscReal              time_step, eval_times[100];
 91:   PetscInt               num_eval_times = PETSC_STATIC_ARRAY_LENGTH(eval_times);
 92:   TSExactFinalTimeOption eftopt;
 93:   char                   dir[16];
 94:   TSIFunctionFn         *ifun;
 95:   const char            *defaultType;
 96:   char                   typeName[256];

 98:   PetscFunctionBegin;

101:   PetscCall(TSRegisterAll());
102:   PetscCall(TSGetIFunction(ts, NULL, &ifun, NULL));

104:   PetscObjectOptionsBegin((PetscObject)ts);
105:   if (((PetscObject)ts)->type_name) defaultType = ((PetscObject)ts)->type_name;
106:   else defaultType = ifun ? TSBEULER : TSEULER;
107:   PetscCall(PetscOptionsFList("-ts_type", "TS method", "TSSetType", TSList, defaultType, typeName, 256, &opt));
108:   if (opt) PetscCall(TSSetType(ts, typeName));
109:   else PetscCall(TSSetType(ts, defaultType));

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

134:   PetscCall(PetscOptionsBool("-ts_rhs_jacobian_test_mult", "Test the RHS Jacobian for consistency with RHS at each solve ", "None", ts->testjacobian, &ts->testjacobian, NULL));
135:   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));
136:   PetscCall(PetscOptionsBool("-ts_use_splitrhsfunction", "Use the split RHS function for multirate solvers ", "TSSetUseSplitRHSFunction", ts->use_splitrhsfunction, &ts->use_splitrhsfunction, NULL));
137: #if defined(PETSC_HAVE_SAWS)
138:   {
139:     PetscBool set;
140:     flg = PETSC_FALSE;
141:     PetscCall(PetscOptionsBool("-ts_saws_block", "Block for SAWs memory snooper at end of TSSolve", "PetscObjectSAWsBlock", ((PetscObject)ts)->amspublishblock, &flg, &set));
142:     if (set) PetscCall(PetscObjectSAWsSetBlock((PetscObject)ts, flg));
143:   }
144: #endif

146:   /* Monitor options */
147:   PetscCall(PetscOptionsInt("-ts_monitor_frequency", "Number of time steps between monitor output", "TSMonitorSetFrequency", ts->monitorFrequency, &ts->monitorFrequency, NULL));
148:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor", "Monitor time and timestep size", "TSMonitorDefault", TSMonitorDefault, NULL));
149:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_extreme", "Monitor extreme values of the solution", "TSMonitorExtreme", TSMonitorExtreme, NULL));
150:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_solution", "View the solution at each timestep", "TSMonitorSolution", TSMonitorSolution, NULL));
151:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_dmswarm_monitor_moments", "Monitor moments of particle distribution", "TSDMSwarmMonitorMoments", TSDMSwarmMonitorMoments, NULL));

153:   PetscCall(PetscOptionsString("-ts_monitor_python", "Use Python function", "TSMonitorSet", NULL, monfilename, sizeof(monfilename), &flg));
154:   if (flg) PetscCall(PetscPythonMonitorSet((PetscObject)ts, monfilename));

156:   PetscCall(PetscOptionsName("-ts_monitor_lg_solution", "Monitor solution graphically", "TSMonitorLGSolution", &opt));
157:   if (opt) {
158:     PetscInt  howoften = 1;
159:     DM        dm;
160:     PetscBool net;

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

177:   PetscCall(PetscOptionsName("-ts_monitor_lg_error", "Monitor error graphically", "TSMonitorLGError", &opt));
178:   if (opt) {
179:     TSMonitorLGCtx ctx;
180:     PetscInt       howoften = 1;

182:     PetscCall(PetscOptionsInt("-ts_monitor_lg_error", "Monitor error graphically", "TSMonitorLGError", howoften, &howoften, NULL));
183:     PetscCall(TSMonitorLGCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
184:     PetscCall(TSMonitorSet(ts, TSMonitorLGError, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
185:   }
186:   PetscCall(TSMonitorSetFromOptions(ts, "-ts_monitor_error", "View the error at each timestep", "TSMonitorError", TSMonitorError, NULL));

188:   PetscCall(PetscOptionsName("-ts_monitor_lg_timestep", "Monitor timestep size graphically", "TSMonitorLGTimeStep", &opt));
189:   if (opt) {
190:     TSMonitorLGCtx ctx;
191:     PetscInt       howoften = 1;

193:     PetscCall(PetscOptionsInt("-ts_monitor_lg_timestep", "Monitor timestep size graphically", "TSMonitorLGTimeStep", howoften, &howoften, NULL));
194:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
195:     PetscCall(TSMonitorSet(ts, TSMonitorLGTimeStep, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
196:   }
197:   PetscCall(PetscOptionsName("-ts_monitor_lg_timestep_log", "Monitor log timestep size graphically", "TSMonitorLGTimeStep", &opt));
198:   if (opt) {
199:     TSMonitorLGCtx ctx;
200:     PetscInt       howoften = 1;

202:     PetscCall(PetscOptionsInt("-ts_monitor_lg_timestep_log", "Monitor log timestep size graphically", "TSMonitorLGTimeStep", howoften, &howoften, NULL));
203:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
204:     PetscCall(TSMonitorSet(ts, TSMonitorLGTimeStep, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
205:     ctx->semilogy = PETSC_TRUE;
206:   }

208:   PetscCall(PetscOptionsName("-ts_monitor_lg_snes_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGSNESIterations", &opt));
209:   if (opt) {
210:     TSMonitorLGCtx ctx;
211:     PetscInt       howoften = 1;

213:     PetscCall(PetscOptionsInt("-ts_monitor_lg_snes_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGSNESIterations", howoften, &howoften, NULL));
214:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
215:     PetscCall(TSMonitorSet(ts, TSMonitorLGSNESIterations, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
216:   }
217:   PetscCall(PetscOptionsName("-ts_monitor_lg_ksp_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGKSPIterations", &opt));
218:   if (opt) {
219:     TSMonitorLGCtx ctx;
220:     PetscInt       howoften = 1;

222:     PetscCall(PetscOptionsInt("-ts_monitor_lg_ksp_iterations", "Monitor number nonlinear iterations for each timestep graphically", "TSMonitorLGKSPIterations", howoften, &howoften, NULL));
223:     PetscCall(TSMonitorLGCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, howoften, &ctx));
224:     PetscCall(TSMonitorSet(ts, TSMonitorLGKSPIterations, ctx, (PetscCtxDestroyFn *)TSMonitorLGCtxDestroy));
225:   }
226:   PetscCall(PetscOptionsName("-ts_monitor_sp_eig", "Monitor eigenvalues of linearized operator graphically", "TSMonitorSPEig", &opt));
227:   if (opt) {
228:     TSMonitorSPEigCtx ctx;
229:     PetscInt          howoften = 1;

231:     PetscCall(PetscOptionsInt("-ts_monitor_sp_eig", "Monitor eigenvalues of linearized operator graphically", "TSMonitorSPEig", howoften, &howoften, NULL));
232:     PetscCall(TSMonitorSPEigCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
233:     PetscCall(TSMonitorSet(ts, TSMonitorSPEig, ctx, (PetscCtxDestroyFn *)TSMonitorSPEigCtxDestroy));
234:   }
235:   PetscCall(PetscOptionsName("-ts_monitor_sp_swarm", "Display particle phase space from the DMSwarm", "TSMonitorSPSwarm", &opt));
236:   if (opt) {
237:     TSMonitorSPCtx ctx;
238:     PetscInt       howoften = 1, retain = 0;
239:     PetscBool      phase = PETSC_TRUE, create = PETSC_TRUE, multispecies = PETSC_FALSE;

241:     for (PetscInt i = 0; i < ts->numbermonitors; ++i)
242:       if (ts->monitor[i] == TSMonitorSPSwarmSolution) {
243:         create = PETSC_FALSE;
244:         break;
245:       }
246:     if (create) {
247:       PetscCall(PetscOptionsInt("-ts_monitor_sp_swarm", "Display particles phase space from the DMSwarm", "TSMonitorSPSwarm", howoften, &howoften, NULL));
248:       PetscCall(PetscOptionsInt("-ts_monitor_sp_swarm_retain", "Retain n points plotted to show trajectory, -1 for all points", "TSMonitorSPSwarm", retain, &retain, NULL));
249:       PetscCall(PetscOptionsBool("-ts_monitor_sp_swarm_phase", "Plot in phase space rather than coordinate space", "TSMonitorSPSwarm", phase, &phase, NULL));
250:       PetscCall(PetscOptionsBool("-ts_monitor_sp_swarm_multi_species", "Color particles by particle species", "TSMonitorSPSwarm", multispecies, &multispecies, NULL));
251:       PetscCall(TSMonitorSPCtxCreate(PetscObjectComm((PetscObject)ts), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, retain, phase, multispecies, &ctx));
252:       PetscCall(TSMonitorSet(ts, TSMonitorSPSwarmSolution, ctx, (PetscCtxDestroyFn *)TSMonitorSPCtxDestroy));
253:     }
254:   }
255:   PetscCall(PetscOptionsName("-ts_monitor_hg_swarm", "Display particle histogram from the DMSwarm", "TSMonitorHGSwarm", &opt));
256:   if (opt) {
257:     TSMonitorHGCtx ctx;
258:     PetscInt       howoften = 1, Ns = 1;
259:     PetscBool      velocity = PETSC_FALSE, create = PETSC_TRUE;

261:     for (PetscInt i = 0; i < ts->numbermonitors; ++i)
262:       if (ts->monitor[i] == TSMonitorHGSwarmSolution) {
263:         create = PETSC_FALSE;
264:         break;
265:       }
266:     if (create) {
267:       DM       sw, dm;
268:       PetscInt Nc, Nb;

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

288:     PetscCall(PetscOptionsInt("-ts_monitor_draw_solution", "Monitor solution graphically", "TSMonitorDrawSolution", howoften, &howoften, NULL));
289:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Computed Solution", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
290:     PetscCall(TSMonitorSet(ts, TSMonitorDrawSolution, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
291:   }
292:   opt = PETSC_FALSE;
293:   PetscCall(PetscOptionsName("-ts_monitor_draw_solution_phase", "Monitor solution graphically", "TSMonitorDrawSolutionPhase", &opt));
294:   if (opt) {
295:     TSMonitorDrawCtx ctx;
296:     PetscReal        bounds[4];
297:     PetscInt         n = 4;
298:     PetscDraw        draw;
299:     PetscDrawAxis    axis;

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

316:     PetscCall(PetscOptionsInt("-ts_monitor_draw_error", "Monitor error graphically", "TSMonitorDrawError", howoften, &howoften, NULL));
317:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Error", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
318:     PetscCall(TSMonitorSet(ts, TSMonitorDrawError, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
319:   }
320:   opt = PETSC_FALSE;
321:   PetscCall(PetscOptionsName("-ts_monitor_draw_solution_function", "Monitor solution provided by TSMonitorSetSolutionFunction() graphically", "TSMonitorDrawSolutionFunction", &opt));
322:   if (opt) {
323:     TSMonitorDrawCtx ctx;
324:     PetscInt         howoften = 1;

326:     PetscCall(PetscOptionsInt("-ts_monitor_draw_solution_function", "Monitor solution provided by TSMonitorSetSolutionFunction() graphically", "TSMonitorDrawSolutionFunction", howoften, &howoften, NULL));
327:     PetscCall(TSMonitorDrawCtxCreate(PetscObjectComm((PetscObject)ts), NULL, "Solution provided by user function", PETSC_DECIDE, PETSC_DECIDE, 300, 300, howoften, &ctx));
328:     PetscCall(TSMonitorSet(ts, TSMonitorDrawSolutionFunction, ctx, (PetscCtxDestroyFn *)TSMonitorDrawCtxDestroy));
329:   }

331:   opt = PETSC_FALSE;
332:   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));
333:   if (flg) {
334:     TSMonitorVTKCtx ctx;

336:     PetscCall(TSMonitorSolutionVTKCtxCreate(monfilename, &ctx));
337:     PetscCall(PetscOptionsInt("-ts_monitor_solution_vtk_interval", "Save every interval time step (-1 for last step only)", NULL, ctx->interval, &ctx->interval, NULL));
338:     PetscCall(TSMonitorSet(ts, (PetscErrorCode (*)(TS, PetscInt, PetscReal, Vec, void *))TSMonitorSolutionVTK, ctx, (PetscCtxDestroyFn *)TSMonitorSolutionVTKDestroy));
339:   }

341:   PetscCall(PetscOptionsString("-ts_monitor_dmda_ray", "Display a ray of the solution", "None", "y=0", dir, sizeof(dir), &flg));
342:   if (flg) {
343:     TSMonitorDMDARayCtx *rayctx;
344:     int                  ray = 0;
345:     DMDirection          ddir;
346:     DM                   da;
347:     PetscMPIInt          rank;

349:     PetscCheck(dir[1] == '=', PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray %s", dir);
350:     if (dir[0] == 'x') ddir = DM_X;
351:     else if (dir[0] == 'y') ddir = DM_Y;
352:     else SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray %s", dir);
353:     sscanf(dir + 2, "%d", &ray);

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

372:     PetscCheck(dir[1] == '=', PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Malformed ray %s", dir);
373:     if (dir[0] == 'x') ddir = DM_X;
374:     else if (dir[0] == 'y') ddir = DM_Y;
375:     else SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Unknown ray direction %s", dir);
376:     sscanf(dir + 2, "%d", &ray);

378:     PetscCall(PetscInfo(ts, "Displaying LG DMDA ray %c = %d\n", dir[0], ray));
379:     PetscCall(PetscNew(&rayctx));
380:     PetscCall(TSGetDM(ts, &da));
381:     PetscCall(DMDAGetRay(da, ddir, ray, &rayctx->ray, &rayctx->scatter));
382:     PetscCall(TSMonitorLGCtxCreate(PETSC_COMM_SELF, NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 600, 400, howoften, &rayctx->lgctx));
383:     PetscCall(TSMonitorSet(ts, TSMonitorLGDMDARay, rayctx, TSMonitorDMDARayDestroy));
384:   }

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

390:     PetscCall(TSMonitorEnvelopeCtxCreate(ts, &ctx));
391:     PetscCall(TSMonitorSet(ts, TSMonitorEnvelope, ctx, (PetscCtxDestroyFn *)TSMonitorEnvelopeCtxDestroy));
392:   }
393:   flg = PETSC_FALSE;
394:   PetscCall(PetscOptionsBool("-ts_monitor_cancel", "Remove all monitors", "TSMonitorCancel", flg, &flg, &opt));
395:   if (opt && flg) PetscCall(TSMonitorCancel(ts));

397:   flg = PETSC_FALSE;
398:   PetscCall(PetscOptionsBool("-ts_fd_color", "Use finite differences with coloring to compute IJacobian", "TSComputeIJacobianDefaultColor", flg, &flg, NULL));
399:   if (flg) {
400:     DM dm;

402:     PetscCall(TSGetDM(ts, &dm));
403:     PetscCall(DMTSUnsetIJacobianContext_Internal(dm));
404:     PetscCall(TSSetIJacobian(ts, NULL, NULL, TSComputeIJacobianDefaultColor, NULL));
405:     PetscCall(PetscInfo(ts, "Setting default finite difference coloring Jacobian matrix\n"));
406:   }

408:   /* Handle specific TS options */
409:   PetscTryTypeMethod(ts, setfromoptions, PetscOptionsObject);

411:   /* Handle TSAdapt options */
412:   PetscCall(TSGetAdapt(ts, &ts->adapt));
413:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));
414:   PetscCall(TSAdaptSetFromOptions(ts->adapt, PetscOptionsObject));

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

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

423:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
424:   PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)ts, PetscOptionsObject));
425:   PetscOptionsEnd();

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

429:   /* why do we have to do this here and not during TSSetUp? */
430:   PetscCall(TSGetSNES(ts, &ts->snes));
431:   if (ts->problem_type == TS_LINEAR) {
432:     PetscCall(PetscObjectTypeCompareAny((PetscObject)ts->snes, &flg, SNESKSPONLY, SNESKSPTRANSPOSEONLY, ""));
433:     if (!flg) PetscCall(SNESSetType(ts->snes, SNESKSPONLY));
434:   }
435:   PetscCall(SNESSetFromOptions(ts->snes));
436:   PetscFunctionReturn(PETSC_SUCCESS);
437: }

439: /*@
440:   TSGetTrajectory - Gets the trajectory from a `TS` if it exists

442:   Collective

444:   Input Parameter:
445: . ts - the `TS` context obtained from `TSCreate()`

447:   Output Parameter:
448: . tr - the `TSTrajectory` object, if it exists

450:   Level: advanced

452:   Note:
453:   This routine should be called after all `TS` options have been set

455: .seealso: [](ch_ts), `TS`, `TSTrajectory`, `TSAdjointSolve()`, `TSTrajectoryCreate()`
456: @*/
457: PetscErrorCode TSGetTrajectory(TS ts, TSTrajectory *tr)
458: {
459:   PetscFunctionBegin;
461:   *tr = ts->trajectory;
462:   PetscFunctionReturn(PETSC_SUCCESS);
463: }

465: /*@
466:   TSSetSaveTrajectory - Causes the `TS` to save its solutions as it iterates forward in time in a `TSTrajectory` object

468:   Collective

470:   Input Parameter:
471: . ts - the `TS` context obtained from `TSCreate()`

473:   Options Database Keys:
474: + -ts_save_trajectory      - saves the trajectory to a file
475: - -ts_trajectory_type type - set trajectory type

477:   Level: intermediate

479:   Notes:
480:   This routine should be called after all `TS` options have been set

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

485: .seealso: [](ch_ts), `TS`, `TSTrajectory`, `TSGetTrajectory()`, `TSAdjointSolve()`
486: @*/
487: PetscErrorCode TSSetSaveTrajectory(TS ts)
488: {
489:   PetscFunctionBegin;
491:   if (!ts->trajectory) PetscCall(TSTrajectoryCreate(PetscObjectComm((PetscObject)ts), &ts->trajectory));
492:   PetscFunctionReturn(PETSC_SUCCESS);
493: }

495: /*@
496:   TSResetTrajectory - Destroys and recreates the internal `TSTrajectory` object

498:   Collective

500:   Input Parameter:
501: . ts - the `TS` context obtained from `TSCreate()`

503:   Level: intermediate

505: .seealso: [](ch_ts), `TSTrajectory`, `TSGetTrajectory()`, `TSAdjointSolve()`, `TSRemoveTrajectory()`
506: @*/
507: PetscErrorCode TSResetTrajectory(TS ts)
508: {
509:   PetscFunctionBegin;
511:   if (ts->trajectory) {
512:     PetscCall(TSTrajectoryDestroy(&ts->trajectory));
513:     PetscCall(TSTrajectoryCreate(PetscObjectComm((PetscObject)ts), &ts->trajectory));
514:   }
515:   PetscFunctionReturn(PETSC_SUCCESS);
516: }

518: /*@
519:   TSRemoveTrajectory - Destroys and removes the internal `TSTrajectory` object from a `TS`

521:   Collective

523:   Input Parameter:
524: . ts - the `TS` context obtained from `TSCreate()`

526:   Level: intermediate

528: .seealso: [](ch_ts), `TSTrajectory`, `TSResetTrajectory()`, `TSAdjointSolve()`
529: @*/
530: PetscErrorCode TSRemoveTrajectory(TS ts)
531: {
532:   PetscFunctionBegin;
534:   if (ts->trajectory) PetscCall(TSTrajectoryDestroy(&ts->trajectory));
535:   PetscFunctionReturn(PETSC_SUCCESS);
536: }

538: /*@
539:   TSComputeRHSJacobian - Computes the Jacobian matrix that has been
540:   set with `TSSetRHSJacobian()`.

542:   Collective

544:   Input Parameters:
545: + ts - the `TS` context
546: . t  - current timestep
547: - U  - input vector

549:   Output Parameters:
550: + A - Jacobian matrix
551: - B - optional matrix used to compute the preconditioner, often the same as `A`

553:   Level: developer

555:   Note:
556:   Most users should not need to explicitly call this routine, as it
557:   is used internally within the ODE integrators.

559: .seealso: [](ch_ts), `TS`, `TSSetRHSJacobian()`, `KSPSetOperators()`
560: @*/
561: PetscErrorCode TSComputeRHSJacobian(TS ts, PetscReal t, Vec U, Mat A, Mat B)
562: {
563:   PetscObjectState Ustate;
564:   PetscObjectId    Uid;
565:   DM               dm;
566:   DMTS             tsdm;
567:   TSRHSJacobianFn *rhsjacobianfunc;
568:   void            *ctx;
569:   TSRHSFunctionFn *rhsfunction;

571:   PetscFunctionBegin;
574:   PetscCheckSameComm(ts, 1, U, 3);
575:   PetscCall(TSGetDM(ts, &dm));
576:   PetscCall(DMGetDMTS(dm, &tsdm));
577:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));
578:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobianfunc, &ctx));
579:   PetscCall(PetscObjectStateGet((PetscObject)U, &Ustate));
580:   PetscCall(PetscObjectGetId((PetscObject)U, &Uid));

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

584:   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);
585:   if (rhsjacobianfunc) {
586:     PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, A, B));
587:     PetscCallBack("TS callback Jacobian", (*rhsjacobianfunc)(ts, t, U, A, B, ctx));
588:     ts->rhsjacs++;
589:     PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, A, B));
590:   } else {
591:     PetscCall(MatZeroEntries(A));
592:     if (B && A != B) PetscCall(MatZeroEntries(B));
593:   }
594:   ts->rhsjacobian.time  = t;
595:   ts->rhsjacobian.shift = 0;
596:   ts->rhsjacobian.scale = 1.;
597:   PetscCall(PetscObjectGetId((PetscObject)U, &ts->rhsjacobian.Xid));
598:   PetscCall(PetscObjectStateGet((PetscObject)U, &ts->rhsjacobian.Xstate));
599:   PetscFunctionReturn(PETSC_SUCCESS);
600: }

602: /*@
603:   TSComputeRHSFunction - Evaluates the right-hand-side function for a `TS`

605:   Collective

607:   Input Parameters:
608: + ts - the `TS` context
609: . t  - current time
610: - U  - state vector

612:   Output Parameter:
613: . y - right-hand side

615:   Level: developer

617:   Note:
618:   Most users should not need to explicitly call this routine, as it
619:   is used internally within the nonlinear solvers.

621: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSComputeIFunction()`
622: @*/
623: PetscErrorCode TSComputeRHSFunction(TS ts, PetscReal t, Vec U, Vec y)
624: {
625:   TSRHSFunctionFn *rhsfunction;
626:   TSIFunctionFn   *ifunction;
627:   void            *ctx;
628:   DM               dm;

630:   PetscFunctionBegin;
634:   PetscCall(TSGetDM(ts, &dm));
635:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, &ctx));
636:   PetscCall(DMTSGetIFunction(dm, &ifunction, NULL));

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

640:   if (rhsfunction) {
641:     PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, y, 0));
642:     PetscCall(VecLockReadPush(U));
643:     PetscCallBack("TS callback right-hand-side", (*rhsfunction)(ts, t, U, y, ctx));
644:     PetscCall(VecLockReadPop(U));
645:     ts->rhsfuncs++;
646:     PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, y, 0));
647:   } else PetscCall(VecZeroEntries(y));
648:   PetscFunctionReturn(PETSC_SUCCESS);
649: }

651: /*@
652:   TSComputeSolutionFunction - Evaluates the solution function.

654:   Collective

656:   Input Parameters:
657: + ts - the `TS` context
658: - t  - current time

660:   Output Parameter:
661: . U - the solution

663:   Level: developer

665: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSSetRHSFunction()`, `TSComputeIFunction()`
666: @*/
667: PetscErrorCode TSComputeSolutionFunction(TS ts, PetscReal t, Vec U)
668: {
669:   TSSolutionFn *solutionfunction;
670:   void         *ctx;
671:   DM            dm;

673:   PetscFunctionBegin;
676:   PetscCall(TSGetDM(ts, &dm));
677:   PetscCall(DMTSGetSolutionFunction(dm, &solutionfunction, &ctx));
678:   if (solutionfunction) PetscCallBack("TS callback solution", (*solutionfunction)(ts, t, U, ctx));
679:   PetscFunctionReturn(PETSC_SUCCESS);
680: }
681: /*@
682:   TSComputeForcingFunction - Evaluates the forcing function.

684:   Collective

686:   Input Parameters:
687: + ts - the `TS` context
688: - t  - current time

690:   Output Parameter:
691: . U - the function value

693:   Level: developer

695: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSSetRHSFunction()`, `TSComputeIFunction()`
696: @*/
697: PetscErrorCode TSComputeForcingFunction(TS ts, PetscReal t, Vec U)
698: {
699:   void        *ctx;
700:   DM           dm;
701:   TSForcingFn *forcing;

703:   PetscFunctionBegin;
706:   PetscCall(TSGetDM(ts, &dm));
707:   PetscCall(DMTSGetForcingFunction(dm, &forcing, &ctx));

709:   if (forcing) PetscCallBack("TS callback forcing function", (*forcing)(ts, t, U, ctx));
710:   PetscFunctionReturn(PETSC_SUCCESS);
711: }

713: PetscErrorCode TSGetRHSMats_Private(TS ts, Mat *Arhs, Mat *Brhs)
714: {
715:   Mat            A, B;
716:   TSIJacobianFn *ijacobian;

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

762: /*@
763:   TSComputeIFunction - Evaluates the DAE residual written in the implicit form F(t,U,Udot)=0

765:   Collective

767:   Input Parameters:
768: + ts   - the `TS` context
769: . t    - current time
770: . U    - state vector
771: . Udot - time derivative of state vector
772: - imex - flag indicates if the method is `TSARKIMEX` so that the RHSFunction should be kept separate

774:   Output Parameter:
775: . Y - right-hand side

777:   Level: developer

779:   Note:
780:   Most users should not need to explicitly call this routine, as it
781:   is used internally within the nonlinear solvers.

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

786: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `TSComputeRHSFunction()`
787: @*/
788: PetscErrorCode TSComputeIFunction(TS ts, PetscReal t, Vec U, Vec Udot, Vec Y, PetscBool imex)
789: {
790:   TSIFunctionFn   *ifunction;
791:   TSRHSFunctionFn *rhsfunction;
792:   void            *ctx;
793:   DM               dm;

795:   PetscFunctionBegin;

801:   PetscCall(TSGetDM(ts, &dm));
802:   PetscCall(DMTSGetIFunction(dm, &ifunction, &ctx));
803:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));

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

807:   PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, Udot, Y));
808:   if (ifunction) {
809:     PetscCallBack("TS callback implicit function", (*ifunction)(ts, t, U, Udot, Y, ctx));
810:     ts->ifuncs++;
811:   }
812:   if (imex) {
813:     if (!ifunction) PetscCall(VecCopy(Udot, Y));
814:   } else if (rhsfunction) {
815:     if (ifunction) {
816:       Vec Frhs;

818:       PetscCall(DMGetGlobalVector(dm, &Frhs));
819:       PetscCall(TSComputeRHSFunction(ts, t, U, Frhs));
820:       PetscCall(VecAXPY(Y, -1, Frhs));
821:       PetscCall(DMRestoreGlobalVector(dm, &Frhs));
822:     } else {
823:       PetscCall(TSComputeRHSFunction(ts, t, U, Y));
824:       PetscCall(VecAYPX(Y, -1, Udot));
825:     }
826:   }
827:   PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, Udot, Y));
828:   PetscFunctionReturn(PETSC_SUCCESS);
829: }

831: /*
832:    TSRecoverRHSJacobian - Recover the Jacobian matrix so that one can call `TSComputeRHSJacobian()` on it.

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

837: */
838: static PetscErrorCode TSRecoverRHSJacobian(TS ts, Mat A, Mat B)
839: {
840:   PetscFunctionBegin;
842:   PetscCheck(A == ts->Arhs, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Invalid Amat");
843:   PetscCheck(B == ts->Brhs, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Invalid Bmat");

845:   if (ts->rhsjacobian.shift) PetscCall(MatShift(A, -ts->rhsjacobian.shift));
846:   if (ts->rhsjacobian.scale == -1.) PetscCall(MatScale(A, -1));
847:   if (B && B == ts->Brhs && A != B) {
848:     if (ts->rhsjacobian.shift) PetscCall(MatShift(B, -ts->rhsjacobian.shift));
849:     if (ts->rhsjacobian.scale == -1.) PetscCall(MatScale(B, -1));
850:   }
851:   ts->rhsjacobian.shift = 0;
852:   ts->rhsjacobian.scale = 1.;
853:   PetscFunctionReturn(PETSC_SUCCESS);
854: }

856: /*@
857:   TSComputeIJacobian - Evaluates the Jacobian of the DAE

859:   Collective

861:   Input Parameters:
862: + ts    - the `TS` context
863: . t     - current timestep
864: . U     - state vector
865: . Udot  - time derivative of state vector
866: . shift - shift to apply, see note below
867: - imex  - flag indicates if the method is `TSARKIMEX` so that the RHSJacobian should be kept separate

869:   Output Parameters:
870: + A - Jacobian matrix
871: - B - matrix from which the preconditioner is constructed; often the same as `A`

873:   Level: developer

875:   Notes:
876:   If F(t,U,Udot)=0 is the DAE, the required Jacobian is
877: .vb
878:    dF/dU + shift*dF/dUdot
879: .ve
880:   Most users should not need to explicitly call this routine, as it
881:   is used internally within the nonlinear solvers.

883: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`
884: @*/
885: PetscErrorCode TSComputeIJacobian(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, PetscBool imex)
886: {
887:   TSIJacobianFn   *ijacobian;
888:   TSRHSJacobianFn *rhsjacobian;
889:   DM               dm;
890:   void            *ctx;

892:   PetscFunctionBegin;

899:   PetscCall(TSGetDM(ts, &dm));
900:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, &ctx));
901:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));

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

905:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, A, B));
906:   if (ijacobian) {
907:     PetscCallBack("TS callback implicit Jacobian", (*ijacobian)(ts, t, U, Udot, shift, A, B, ctx));
908:     ts->ijacs++;
909:   }
910:   if (imex) {
911:     if (!ijacobian) { /* system was written as Udot = G(t,U) */
912:       PetscBool assembled;
913:       if (rhsjacobian) {
914:         Mat Arhs = NULL;
915:         PetscCall(TSGetRHSMats_Private(ts, &Arhs, NULL));
916:         if (A == Arhs) {
917:           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 */
918:           ts->rhsjacobian.time = PETSC_MIN_REAL;
919:         }
920:       }
921:       PetscCall(MatZeroEntries(A));
922:       PetscCall(MatAssembled(A, &assembled));
923:       if (!assembled) {
924:         PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
925:         PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
926:       }
927:       PetscCall(MatShift(A, shift));
928:       if (A != B) {
929:         PetscCall(MatZeroEntries(B));
930:         PetscCall(MatAssembled(B, &assembled));
931:         if (!assembled) {
932:           PetscCall(MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY));
933:           PetscCall(MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY));
934:         }
935:         PetscCall(MatShift(B, shift));
936:       }
937:     }
938:   } else {
939:     Mat Arhs = NULL, Brhs = NULL;

941:     /* RHSJacobian needs to be converted to part of IJacobian if exists */
942:     if (rhsjacobian) PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
943:     if (Arhs == A) { /* No IJacobian matrix, so we only have the RHS matrix */
944:       PetscObjectState Ustate;
945:       PetscObjectId    Uid;
946:       TSRHSFunctionFn *rhsfunction;

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

958:         if (ts->rhsjacobian.reuse) { /* Undo the damage */
959:           /* MatScale has a short path for this case.
960:              However, this code path is taken the first time TSComputeRHSJacobian is called
961:              and the matrices have not been assembled yet */
962:           PetscCall(TSRecoverRHSJacobian(ts, A, B));
963:         }
964:         PetscCall(TSComputeRHSJacobian(ts, t, U, A, B));
965:         PetscCall(SNESGetUseMatrixFree(ts->snes, NULL, &flg));
966:         /* since -snes_mf_operator uses the full SNES function it does not need to be shifted or scaled here */
967:         if (!flg) {
968:           PetscCall(MatScale(A, -1));
969:           PetscCall(MatShift(A, shift));
970:         }
971:         if (A != B) {
972:           PetscCall(MatScale(B, -1));
973:           PetscCall(MatShift(B, shift));
974:         }
975:       }
976:       ts->rhsjacobian.scale = -1;
977:       ts->rhsjacobian.shift = shift;
978:     } else if (Arhs) {  /* Both IJacobian and RHSJacobian */
979:       if (!ijacobian) { /* No IJacobian provided, but we have a separate RHS matrix */
980:         PetscCall(MatZeroEntries(A));
981:         PetscCall(MatShift(A, shift));
982:         if (A != B) {
983:           PetscCall(MatZeroEntries(B));
984:           PetscCall(MatShift(B, shift));
985:         }
986:       }
987:       PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
988:       PetscCall(MatAXPY(A, -1, Arhs, ts->axpy_pattern));
989:       if (A != B) PetscCall(MatAXPY(B, -1, Brhs, ts->axpy_pattern));
990:     }
991:   }
992:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, A, B));
993:   PetscFunctionReturn(PETSC_SUCCESS);
994: }

996: /*@C
997:   TSSetRHSFunction - Sets the routine for evaluating the function,
998:   where U_t = G(t,u).

1000:   Logically Collective

1002:   Input Parameters:
1003: + ts  - the `TS` context obtained from `TSCreate()`
1004: . r   - vector to put the computed right-hand side (or `NULL` to have it created)
1005: . f   - routine for evaluating the right-hand-side function
1006: - ctx - [optional] user-defined context for private data for the function evaluation routine (may be `NULL`)

1008:   Level: beginner

1010:   Note:
1011:   You must call this function or `TSSetIFunction()` to define your ODE. You cannot use this function when solving a DAE.

1013: .seealso: [](ch_ts), `TS`, `TSRHSFunctionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSSetIFunction()`
1014: @*/
1015: PetscErrorCode TSSetRHSFunction(TS ts, Vec r, TSRHSFunctionFn *f, void *ctx)
1016: {
1017:   SNES snes;
1018:   Vec  ralloc = NULL;
1019:   DM   dm;

1021:   PetscFunctionBegin;

1025:   PetscCall(TSGetDM(ts, &dm));
1026:   PetscCall(DMTSSetRHSFunction(dm, f, ctx));
1027:   PetscCall(TSGetSNES(ts, &snes));
1028:   if (!r && !ts->dm && ts->vec_sol) {
1029:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1030:     r = ralloc;
1031:   }
1032:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1033:   PetscCall(VecDestroy(&ralloc));
1034:   PetscFunctionReturn(PETSC_SUCCESS);
1035: }

1037: /*@C
1038:   TSSetSolutionFunction - Provide a function that computes the solution of the ODE or DAE

1040:   Logically Collective

1042:   Input Parameters:
1043: + ts  - the `TS` context obtained from `TSCreate()`
1044: . f   - routine for evaluating the solution
1045: - ctx - [optional] user-defined context for private data for the
1046:           function evaluation routine (may be `NULL`)

1048:   Options Database Keys:
1049: + -ts_monitor_lg_error   - create a graphical monitor of error history, requires user to have provided `TSSetSolutionFunction()`
1050: - -ts_monitor_draw_error - Monitor error graphically, requires user to have provided `TSSetSolutionFunction()`

1052:   Level: intermediate

1054:   Notes:
1055:   This routine is used for testing accuracy of time integration schemes when you already know the solution.
1056:   If analytic solutions are not known for your system, consider using the Method of Manufactured Solutions to
1057:   create closed-form solutions with non-physical forcing terms.

1059:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1061: .seealso: [](ch_ts), `TS`, `TSSolutionFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`, `TSComputeSolutionFunction()`, `TSSetForcingFunction()`, `TSSetSolution()`, `TSGetSolution()`, `TSMonitorLGError()`, `TSMonitorDrawError()`
1062: @*/
1063: PetscErrorCode TSSetSolutionFunction(TS ts, TSSolutionFn *f, void *ctx)
1064: {
1065:   DM dm;

1067:   PetscFunctionBegin;
1069:   PetscCall(TSGetDM(ts, &dm));
1070:   PetscCall(DMTSSetSolutionFunction(dm, f, ctx));
1071:   PetscFunctionReturn(PETSC_SUCCESS);
1072: }

1074: /*@C
1075:   TSSetForcingFunction - Provide a function that computes a forcing term for a ODE or PDE

1077:   Logically Collective

1079:   Input Parameters:
1080: + ts   - the `TS` context obtained from `TSCreate()`
1081: . func - routine for evaluating the forcing function
1082: - ctx  - [optional] user-defined context for private data for the function evaluation routine
1083:          (may be `NULL`)

1085:   Level: intermediate

1087:   Notes:
1088:   This routine is useful for testing accuracy of time integration schemes when using the Method of Manufactured Solutions to
1089:   create closed-form solutions with a non-physical forcing term. It allows you to use the Method of Manufactored Solution without directly editing the
1090:   definition of the problem you are solving and hence possibly introducing bugs.

1092:   This replaces the ODE F(u,u_t,t) = 0 the `TS` is solving with F(u,u_t,t) - func(t) = 0

1094:   This forcing function does not depend on the solution to the equations, it can only depend on spatial location, time, and possibly parameters, the
1095:   parameters can be passed in the ctx variable.

1097:   For low-dimensional problems solved in serial, such as small discrete systems, `TSMonitorLGError()` can be used to monitor the error history.

1099: .seealso: [](ch_ts), `TS`, `TSForcingFn`, `TSSetRHSJacobian()`, `TSSetIJacobian()`,
1100: `TSComputeSolutionFunction()`, `TSSetSolutionFunction()`
1101: @*/
1102: PetscErrorCode TSSetForcingFunction(TS ts, TSForcingFn *func, void *ctx)
1103: {
1104:   DM dm;

1106:   PetscFunctionBegin;
1108:   PetscCall(TSGetDM(ts, &dm));
1109:   PetscCall(DMTSSetForcingFunction(dm, func, ctx));
1110:   PetscFunctionReturn(PETSC_SUCCESS);
1111: }

1113: /*@C
1114:   TSSetRHSJacobian - Sets the function to compute the Jacobian of G,
1115:   where U_t = G(U,t), as well as the location to store the matrix.

1117:   Logically Collective

1119:   Input Parameters:
1120: + ts   - the `TS` context obtained from `TSCreate()`
1121: . Amat - (approximate) location to store Jacobian matrix entries computed by `f`
1122: . Pmat - matrix from which preconditioner is to be constructed (usually the same as `Amat`)
1123: . f    - the Jacobian evaluation routine
1124: - ctx  - [optional] user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1126:   Level: beginner

1128:   Notes:
1129:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1131:   The `TS` solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f()`
1132:   You should not assume the values are the same in the next call to f() as you set them in the previous call.

1134: .seealso: [](ch_ts), `TS`, `TSRHSJacobianFn`, `SNESComputeJacobianDefaultColor()`,
1135: `TSSetRHSFunction()`, `TSRHSJacobianSetReuse()`, `TSSetIJacobian()`, `TSRHSFunctionFn`, `TSIFunctionFn`
1136: @*/
1137: PetscErrorCode TSSetRHSJacobian(TS ts, Mat Amat, Mat Pmat, TSRHSJacobianFn *f, void *ctx)
1138: {
1139:   SNES           snes;
1140:   DM             dm;
1141:   TSIJacobianFn *ijacobian;

1143:   PetscFunctionBegin;
1147:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1148:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1150:   PetscCall(TSGetDM(ts, &dm));
1151:   PetscCall(DMTSSetRHSJacobian(dm, f, ctx));
1152:   PetscCall(DMTSGetIJacobian(dm, &ijacobian, NULL));
1153:   PetscCall(TSGetSNES(ts, &snes));
1154:   if (!ijacobian) PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1155:   if (Amat) {
1156:     PetscCall(PetscObjectReference((PetscObject)Amat));
1157:     PetscCall(MatDestroy(&ts->Arhs));
1158:     ts->Arhs = Amat;
1159:   }
1160:   if (Pmat) {
1161:     PetscCall(PetscObjectReference((PetscObject)Pmat));
1162:     PetscCall(MatDestroy(&ts->Brhs));
1163:     ts->Brhs = Pmat;
1164:   }
1165:   PetscFunctionReturn(PETSC_SUCCESS);
1166: }

1168: /*@C
1169:   TSSetIFunction - Set the function to compute F(t,U,U_t) where F() = 0 is the DAE to be solved.

1171:   Logically Collective

1173:   Input Parameters:
1174: + ts  - the `TS` context obtained from `TSCreate()`
1175: . r   - vector to hold the residual (or `NULL` to have it created internally)
1176: . f   - the function evaluation routine
1177: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1179:   Level: beginner

1181:   Note:
1182:   The user MUST call either this routine or `TSSetRHSFunction()` to define the ODE.  When solving DAEs you must use this function.

1184: .seealso: [](ch_ts), `TS`, `TSIFunctionFn`, `TSSetRHSJacobian()`, `TSSetRHSFunction()`,
1185: `TSSetIJacobian()`
1186: @*/
1187: PetscErrorCode TSSetIFunction(TS ts, Vec r, TSIFunctionFn *f, void *ctx)
1188: {
1189:   SNES snes;
1190:   Vec  ralloc = NULL;
1191:   DM   dm;

1193:   PetscFunctionBegin;

1197:   PetscCall(TSGetDM(ts, &dm));
1198:   PetscCall(DMTSSetIFunction(dm, f, ctx));

1200:   PetscCall(TSGetSNES(ts, &snes));
1201:   if (!r && !ts->dm && ts->vec_sol) {
1202:     PetscCall(VecDuplicate(ts->vec_sol, &ralloc));
1203:     r = ralloc;
1204:   }
1205:   PetscCall(SNESSetFunction(snes, r, SNESTSFormFunction, ts));
1206:   PetscCall(VecDestroy(&ralloc));
1207:   PetscFunctionReturn(PETSC_SUCCESS);
1208: }

1210: /*@C
1211:   TSGetIFunction - Returns the vector where the implicit residual is stored and the function/context to compute it.

1213:   Not Collective

1215:   Input Parameter:
1216: . ts - the `TS` context

1218:   Output Parameters:
1219: + r    - vector to hold residual (or `NULL`)
1220: . func - the function to compute residual (or `NULL`)
1221: - ctx  - the function context (or `NULL`)

1223:   Level: advanced

1225: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`
1226: @*/
1227: PetscErrorCode TSGetIFunction(TS ts, Vec *r, TSIFunctionFn **func, void **ctx)
1228: {
1229:   SNES snes;
1230:   DM   dm;

1232:   PetscFunctionBegin;
1234:   PetscCall(TSGetSNES(ts, &snes));
1235:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1236:   PetscCall(TSGetDM(ts, &dm));
1237:   PetscCall(DMTSGetIFunction(dm, func, ctx));
1238:   PetscFunctionReturn(PETSC_SUCCESS);
1239: }

1241: /*@C
1242:   TSGetRHSFunction - Returns the vector where the right-hand side is stored and the function/context to compute it.

1244:   Not Collective

1246:   Input Parameter:
1247: . ts - the `TS` context

1249:   Output Parameters:
1250: + r    - vector to hold computed right-hand side (or `NULL`)
1251: . func - the function to compute right-hand side (or `NULL`)
1252: - ctx  - the function context (or `NULL`)

1254:   Level: advanced

1256: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `SNESGetFunction()`
1257: @*/
1258: PetscErrorCode TSGetRHSFunction(TS ts, Vec *r, TSRHSFunctionFn **func, void **ctx)
1259: {
1260:   SNES snes;
1261:   DM   dm;

1263:   PetscFunctionBegin;
1265:   PetscCall(TSGetSNES(ts, &snes));
1266:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1267:   PetscCall(TSGetDM(ts, &dm));
1268:   PetscCall(DMTSGetRHSFunction(dm, func, ctx));
1269:   PetscFunctionReturn(PETSC_SUCCESS);
1270: }

1272: /*@C
1273:   TSSetIJacobian - Set the function to compute the matrix dF/dU + a*dF/dU_t where F(t,U,U_t) is the function
1274:   provided with `TSSetIFunction()`.

1276:   Logically Collective

1278:   Input Parameters:
1279: + ts   - the `TS` context obtained from `TSCreate()`
1280: . Amat - (approximate) matrix to store Jacobian entries computed by `f`
1281: . Pmat - matrix used to compute preconditioner (usually the same as `Amat`)
1282: . f    - the Jacobian evaluation routine
1283: - ctx  - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1285:   Level: beginner

1287:   Notes:
1288:   The matrices `Amat` and `Pmat` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1290:   If you know the operator Amat has a null space you can use `MatSetNullSpace()` and `MatSetTransposeNullSpace()` to supply the null
1291:   space to `Amat` and the `KSP` solvers will automatically use that null space as needed during the solution process.

1293:   The matrix dF/dU + a*dF/dU_t you provide turns out to be
1294:   the Jacobian of F(t,U,W+a*U) where F(t,U,U_t) = 0 is the DAE to be solved.
1295:   The time integrator internally approximates U_t by W+a*U where the positive "shift"
1296:   a and vector W depend on the integration method, step size, and past states. For example with
1297:   the backward Euler method a = 1/dt and W = -a*U(previous timestep) so
1298:   W + a*U = a*(U - U(previous timestep)) = (U - U(previous timestep))/dt

1300:   You must set all the diagonal entries of the matrices, if they are zero you must still set them with a zero value

1302:   The TS solver may modify the nonzero structure and the entries of the matrices `Amat` and `Pmat` between the calls to `f`
1303:   You should not assume the values are the same in the next call to `f` as you set them in the previous call.

1305:   In case `TSSetRHSJacobian()` is also used in conjunction with a fully-implicit solver,
1306:   multilevel linear solvers, e.g. `PCMG`, will likely not work due to the way `TS` handles rhs matrices.

1308: .seealso: [](ch_ts), `TS`, `TSIJacobianFn`, `TSSetIFunction()`, `TSSetRHSJacobian()`,
1309: `SNESComputeJacobianDefaultColor()`, `SNESComputeJacobianDefault()`, `TSSetRHSFunction()`
1310: @*/
1311: PetscErrorCode TSSetIJacobian(TS ts, Mat Amat, Mat Pmat, TSIJacobianFn *f, void *ctx)
1312: {
1313:   SNES snes;
1314:   DM   dm;

1316:   PetscFunctionBegin;
1320:   if (Amat) PetscCheckSameComm(ts, 1, Amat, 2);
1321:   if (Pmat) PetscCheckSameComm(ts, 1, Pmat, 3);

1323:   PetscCall(TSGetDM(ts, &dm));
1324:   PetscCall(DMTSSetIJacobian(dm, f, ctx));

1326:   PetscCall(TSGetSNES(ts, &snes));
1327:   PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESTSFormJacobian, ts));
1328:   PetscFunctionReturn(PETSC_SUCCESS);
1329: }

1331: /*@
1332:   TSRHSJacobianSetReuse - restore the RHS Jacobian before calling the user-provided `TSRHSJacobianFn` function again

1334:   Logically Collective

1336:   Input Parameters:
1337: + ts    - `TS` context obtained from `TSCreate()`
1338: - reuse - `PETSC_TRUE` if the RHS Jacobian

1340:   Level: intermediate

1342:   Notes:
1343:   Without this flag, `TS` will change the sign and shift the RHS Jacobian for a
1344:   finite-time-step implicit solve, in which case the user function will need to recompute the
1345:   entire Jacobian.  The `reuse `flag must be set if the evaluation function assumes that the
1346:   matrix entries have not been changed by the `TS`.

1348: .seealso: [](ch_ts), `TS`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
1349: @*/
1350: PetscErrorCode TSRHSJacobianSetReuse(TS ts, PetscBool reuse)
1351: {
1352:   PetscFunctionBegin;
1353:   ts->rhsjacobian.reuse = reuse;
1354:   PetscFunctionReturn(PETSC_SUCCESS);
1355: }

1357: /*@C
1358:   TSSetI2Function - Set the function to compute F(t,U,U_t,U_tt) where F = 0 is the DAE to be solved.

1360:   Logically Collective

1362:   Input Parameters:
1363: + ts  - the `TS` context obtained from `TSCreate()`
1364: . F   - vector to hold the residual (or `NULL` to have it created internally)
1365: . fun - the function evaluation routine
1366: - ctx - user-defined context for private data for the function evaluation routine (may be `NULL`)

1368:   Level: beginner

1370: .seealso: [](ch_ts), `TS`, `TSI2FunctionFn`, `TSSetI2Jacobian()`, `TSSetIFunction()`,
1371: `TSCreate()`, `TSSetRHSFunction()`
1372: @*/
1373: PetscErrorCode TSSetI2Function(TS ts, Vec F, TSI2FunctionFn *fun, void *ctx)
1374: {
1375:   DM dm;

1377:   PetscFunctionBegin;
1380:   PetscCall(TSSetIFunction(ts, F, NULL, NULL));
1381:   PetscCall(TSGetDM(ts, &dm));
1382:   PetscCall(DMTSSetI2Function(dm, fun, ctx));
1383:   PetscFunctionReturn(PETSC_SUCCESS);
1384: }

1386: /*@C
1387:   TSGetI2Function - Returns the vector where the implicit residual is stored and the function/context to compute it.

1389:   Not Collective

1391:   Input Parameter:
1392: . ts - the `TS` context

1394:   Output Parameters:
1395: + r   - vector to hold residual (or `NULL`)
1396: . fun - the function to compute residual (or `NULL`)
1397: - ctx - the function context (or `NULL`)

1399:   Level: advanced

1401: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `SNESGetFunction()`, `TSCreate()`
1402: @*/
1403: PetscErrorCode TSGetI2Function(TS ts, Vec *r, TSI2FunctionFn **fun, void **ctx)
1404: {
1405:   SNES snes;
1406:   DM   dm;

1408:   PetscFunctionBegin;
1410:   PetscCall(TSGetSNES(ts, &snes));
1411:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
1412:   PetscCall(TSGetDM(ts, &dm));
1413:   PetscCall(DMTSGetI2Function(dm, fun, ctx));
1414:   PetscFunctionReturn(PETSC_SUCCESS);
1415: }

1417: /*@C
1418:   TSSetI2Jacobian - Set the function to compute the matrix dF/dU + v*dF/dU_t  + a*dF/dU_tt
1419:   where F(t,U,U_t,U_tt) is the function you provided with `TSSetI2Function()`.

1421:   Logically Collective

1423:   Input Parameters:
1424: + ts  - the `TS` context obtained from `TSCreate()`
1425: . J   - matrix to hold the Jacobian values
1426: . P   - matrix for constructing the preconditioner (may be same as `J`)
1427: . jac - the Jacobian evaluation routine, see `TSI2JacobianFn` for the calling sequence
1428: - ctx - user-defined context for private data for the Jacobian evaluation routine (may be `NULL`)

1430:   Level: beginner

1432:   Notes:
1433:   The matrices `J` and `P` are exactly the matrices that are used by `SNES` for the nonlinear solve.

1435:   The matrix dF/dU + v*dF/dU_t + a*dF/dU_tt you provide turns out to be
1436:   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.
1437:   The time integrator internally approximates U_t by W+v*U and U_tt by W'+a*U  where the positive "shift"
1438:   parameters 'v' and 'a' and vectors W, W' depend on the integration method, step size, and past states.

1440: .seealso: [](ch_ts), `TS`, `TSI2JacobianFn`, `TSSetI2Function()`, `TSGetI2Jacobian()`
1441: @*/
1442: PetscErrorCode TSSetI2Jacobian(TS ts, Mat J, Mat P, TSI2JacobianFn *jac, void *ctx)
1443: {
1444:   DM dm;

1446:   PetscFunctionBegin;
1450:   PetscCall(TSSetIJacobian(ts, J, P, NULL, NULL));
1451:   PetscCall(TSGetDM(ts, &dm));
1452:   PetscCall(DMTSSetI2Jacobian(dm, jac, ctx));
1453:   PetscFunctionReturn(PETSC_SUCCESS);
1454: }

1456: /*@C
1457:   TSGetI2Jacobian - Returns the implicit Jacobian at the present timestep.

1459:   Not Collective, but parallel objects are returned if `TS` is parallel

1461:   Input Parameter:
1462: . ts - The `TS` context obtained from `TSCreate()`

1464:   Output Parameters:
1465: + J   - The (approximate) Jacobian of F(t,U,U_t,U_tt)
1466: . P   - The matrix from which the preconditioner is constructed, often the same as `J`
1467: . jac - The function to compute the Jacobian matrices
1468: - ctx - User-defined context for Jacobian evaluation routine

1470:   Level: advanced

1472:   Note:
1473:   You can pass in `NULL` for any return argument you do not need.

1475: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`, `TSSetI2Jacobian()`, `TSGetI2Function()`, `TSCreate()`
1476: @*/
1477: PetscErrorCode TSGetI2Jacobian(TS ts, Mat *J, Mat *P, TSI2JacobianFn **jac, void **ctx)
1478: {
1479:   SNES snes;
1480:   DM   dm;

1482:   PetscFunctionBegin;
1483:   PetscCall(TSGetSNES(ts, &snes));
1484:   PetscCall(SNESSetUpMatrices(snes));
1485:   PetscCall(SNESGetJacobian(snes, J, P, NULL, NULL));
1486:   PetscCall(TSGetDM(ts, &dm));
1487:   PetscCall(DMTSGetI2Jacobian(dm, jac, ctx));
1488:   PetscFunctionReturn(PETSC_SUCCESS);
1489: }

1491: /*@
1492:   TSComputeI2Function - Evaluates the DAE residual written in implicit form F(t,U,U_t,U_tt) = 0

1494:   Collective

1496:   Input Parameters:
1497: + ts - the `TS` context
1498: . t  - current time
1499: . U  - state vector
1500: . V  - time derivative of state vector (U_t)
1501: - A  - second time derivative of state vector (U_tt)

1503:   Output Parameter:
1504: . F - the residual vector

1506:   Level: developer

1508:   Note:
1509:   Most users should not need to explicitly call this routine, as it
1510:   is used internally within the nonlinear solvers.

1512: .seealso: [](ch_ts), `TS`, `TSSetI2Function()`, `TSGetI2Function()`
1513: @*/
1514: PetscErrorCode TSComputeI2Function(TS ts, PetscReal t, Vec U, Vec V, Vec A, Vec F)
1515: {
1516:   DM               dm;
1517:   TSI2FunctionFn  *I2Function;
1518:   void            *ctx;
1519:   TSRHSFunctionFn *rhsfunction;

1521:   PetscFunctionBegin;

1528:   PetscCall(TSGetDM(ts, &dm));
1529:   PetscCall(DMTSGetI2Function(dm, &I2Function, &ctx));
1530:   PetscCall(DMTSGetRHSFunction(dm, &rhsfunction, NULL));

1532:   if (!I2Function) {
1533:     PetscCall(TSComputeIFunction(ts, t, U, A, F, PETSC_FALSE));
1534:     PetscFunctionReturn(PETSC_SUCCESS);
1535:   }

1537:   PetscCall(PetscLogEventBegin(TS_FunctionEval, U, ts, V, F));

1539:   PetscCallBack("TS callback implicit function", I2Function(ts, t, U, V, A, F, ctx));

1541:   if (rhsfunction) {
1542:     Vec Frhs;

1544:     PetscCall(DMGetGlobalVector(dm, &Frhs));
1545:     PetscCall(TSComputeRHSFunction(ts, t, U, Frhs));
1546:     PetscCall(VecAXPY(F, -1, Frhs));
1547:     PetscCall(DMRestoreGlobalVector(dm, &Frhs));
1548:   }

1550:   PetscCall(PetscLogEventEnd(TS_FunctionEval, U, ts, V, F));
1551:   PetscFunctionReturn(PETSC_SUCCESS);
1552: }

1554: /*@
1555:   TSComputeI2Jacobian - Evaluates the Jacobian of the DAE

1557:   Collective

1559:   Input Parameters:
1560: + ts     - the `TS` context
1561: . t      - current timestep
1562: . U      - state vector
1563: . V      - time derivative of state vector
1564: . A      - second time derivative of state vector
1565: . shiftV - shift to apply, see note below
1566: - shiftA - shift to apply, see note below

1568:   Output Parameters:
1569: + J - Jacobian matrix
1570: - P - optional matrix used to construct the preconditioner

1572:   Level: developer

1574:   Notes:
1575:   If $F(t,U,V,A) = 0$ is the DAE, the required Jacobian is

1577: $$
1578:   dF/dU + shiftV*dF/dV + shiftA*dF/dA
1579: $$

1581:   Most users should not need to explicitly call this routine, as it
1582:   is used internally within the ODE integrators.

1584: .seealso: [](ch_ts), `TS`, `TSSetI2Jacobian()`
1585: @*/
1586: PetscErrorCode TSComputeI2Jacobian(TS ts, PetscReal t, Vec U, Vec V, Vec A, PetscReal shiftV, PetscReal shiftA, Mat J, Mat P)
1587: {
1588:   DM               dm;
1589:   TSI2JacobianFn  *I2Jacobian;
1590:   void            *ctx;
1591:   TSRHSJacobianFn *rhsjacobian;

1593:   PetscFunctionBegin;

1601:   PetscCall(TSGetDM(ts, &dm));
1602:   PetscCall(DMTSGetI2Jacobian(dm, &I2Jacobian, &ctx));
1603:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjacobian, NULL));

1605:   if (!I2Jacobian) {
1606:     PetscCall(TSComputeIJacobian(ts, t, U, A, shiftA, J, P, PETSC_FALSE));
1607:     PetscFunctionReturn(PETSC_SUCCESS);
1608:   }

1610:   PetscCall(PetscLogEventBegin(TS_JacobianEval, U, ts, J, P));
1611:   PetscCallBack("TS callback implicit Jacobian", I2Jacobian(ts, t, U, V, A, shiftV, shiftA, J, P, ctx));
1612:   if (rhsjacobian) {
1613:     Mat Jrhs, Prhs;
1614:     PetscCall(TSGetRHSMats_Private(ts, &Jrhs, &Prhs));
1615:     PetscCall(TSComputeRHSJacobian(ts, t, U, Jrhs, Prhs));
1616:     PetscCall(MatAXPY(J, -1, Jrhs, ts->axpy_pattern));
1617:     if (P != J) PetscCall(MatAXPY(P, -1, Prhs, ts->axpy_pattern));
1618:   }

1620:   PetscCall(PetscLogEventEnd(TS_JacobianEval, U, ts, J, P));
1621:   PetscFunctionReturn(PETSC_SUCCESS);
1622: }

1624: /*@C
1625:   TSSetTransientVariable - sets function to transform from state to transient variables

1627:   Logically Collective

1629:   Input Parameters:
1630: + ts   - time stepping context on which to change the transient variable
1631: . tvar - a function that transforms to transient variables, see `TSTransientVariableFn` for the calling sequence
1632: - ctx  - a context for tvar

1634:   Level: advanced

1636:   Notes:
1637:   This is typically used to transform from primitive to conservative variables so that a time integrator (e.g., `TSBDF`)
1638:   can be conservative.  In this context, primitive variables P are used to model the state (e.g., because they lead to
1639:   well-conditioned formulations even in limiting cases such as low-Mach or zero porosity).  The transient variable is
1640:   C(P), specified by calling this function.  An IFunction thus receives arguments (P, Cdot) and the IJacobian must be
1641:   evaluated via the chain rule, as in
1642: .vb
1643:      dF/dP + shift * dF/dCdot dC/dP.
1644: .ve

1646: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSTransientVariableFn`, `DMTSSetTransientVariable()`, `DMTSGetTransientVariable()`, `TSSetIFunction()`, `TSSetIJacobian()`
1647: @*/
1648: PetscErrorCode TSSetTransientVariable(TS ts, TSTransientVariableFn *tvar, void *ctx)
1649: {
1650:   DM dm;

1652:   PetscFunctionBegin;
1654:   PetscCall(TSGetDM(ts, &dm));
1655:   PetscCall(DMTSSetTransientVariable(dm, tvar, ctx));
1656:   PetscFunctionReturn(PETSC_SUCCESS);
1657: }

1659: /*@
1660:   TSComputeTransientVariable - transforms state (primitive) variables to transient (conservative) variables

1662:   Logically Collective

1664:   Input Parameters:
1665: + ts - TS on which to compute
1666: - U  - state vector to be transformed to transient variables

1668:   Output Parameter:
1669: . C - transient (conservative) variable

1671:   Level: developer

1673:   Developer Notes:
1674:   If `DMTSSetTransientVariable()` has not been called, then C is not modified in this routine and C = `NULL` is allowed.
1675:   This makes it safe to call without a guard.  One can use `TSHasTransientVariable()` to check if transient variables are
1676:   being used.

1678: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeIFunction()`, `TSComputeIJacobian()`
1679: @*/
1680: PetscErrorCode TSComputeTransientVariable(TS ts, Vec U, Vec C)
1681: {
1682:   DM   dm;
1683:   DMTS dmts;

1685:   PetscFunctionBegin;
1688:   PetscCall(TSGetDM(ts, &dm));
1689:   PetscCall(DMGetDMTS(dm, &dmts));
1690:   if (dmts->ops->transientvar) {
1692:     PetscCall((*dmts->ops->transientvar)(ts, U, C, dmts->transientvarctx));
1693:   }
1694:   PetscFunctionReturn(PETSC_SUCCESS);
1695: }

1697: /*@
1698:   TSHasTransientVariable - determine whether transient variables have been set

1700:   Logically Collective

1702:   Input Parameter:
1703: . ts - `TS` on which to compute

1705:   Output Parameter:
1706: . has - `PETSC_TRUE` if transient variables have been set

1708:   Level: developer

1710: .seealso: [](ch_ts), `TS`, `TSBDF`, `DMTSSetTransientVariable()`, `TSComputeTransientVariable()`
1711: @*/
1712: PetscErrorCode TSHasTransientVariable(TS ts, PetscBool *has)
1713: {
1714:   DM   dm;
1715:   DMTS dmts;

1717:   PetscFunctionBegin;
1719:   PetscCall(TSGetDM(ts, &dm));
1720:   PetscCall(DMGetDMTS(dm, &dmts));
1721:   *has = dmts->ops->transientvar ? PETSC_TRUE : PETSC_FALSE;
1722:   PetscFunctionReturn(PETSC_SUCCESS);
1723: }

1725: /*@
1726:   TS2SetSolution - Sets the initial solution and time derivative vectors
1727:   for use by the `TS` routines handling second order equations.

1729:   Logically Collective

1731:   Input Parameters:
1732: + ts - the `TS` context obtained from `TSCreate()`
1733: . u  - the solution vector
1734: - v  - the time derivative vector

1736:   Level: beginner

1738: .seealso: [](ch_ts), `TS`
1739: @*/
1740: PetscErrorCode TS2SetSolution(TS ts, Vec u, Vec v)
1741: {
1742:   PetscFunctionBegin;
1746:   PetscCall(TSSetSolution(ts, u));
1747:   PetscCall(PetscObjectReference((PetscObject)v));
1748:   PetscCall(VecDestroy(&ts->vec_dot));
1749:   ts->vec_dot = v;
1750:   PetscFunctionReturn(PETSC_SUCCESS);
1751: }

1753: /*@
1754:   TS2GetSolution - Returns the solution and time derivative at the present timestep
1755:   for second order equations.

1757:   Not Collective

1759:   Input Parameter:
1760: . ts - the `TS` context obtained from `TSCreate()`

1762:   Output Parameters:
1763: + u - the vector containing the solution
1764: - v - the vector containing the time derivative

1766:   Level: intermediate

1768:   Notes:
1769:   It is valid to call this routine inside the function
1770:   that you are evaluating in order to move to the new timestep. This vector not
1771:   changed until the solution at the next timestep has been calculated.

1773: .seealso: [](ch_ts), `TS`, `TS2SetSolution()`, `TSGetTimeStep()`, `TSGetTime()`
1774: @*/
1775: PetscErrorCode TS2GetSolution(TS ts, Vec *u, Vec *v)
1776: {
1777:   PetscFunctionBegin;
1779:   if (u) PetscAssertPointer(u, 2);
1780:   if (v) PetscAssertPointer(v, 3);
1781:   if (u) *u = ts->vec_sol;
1782:   if (v) *v = ts->vec_dot;
1783:   PetscFunctionReturn(PETSC_SUCCESS);
1784: }

1786: /*@
1787:   TSLoad - Loads a `TS` that has been stored in binary  with `TSView()`.

1789:   Collective

1791:   Input Parameters:
1792: + ts     - the newly loaded `TS`, this needs to have been created with `TSCreate()` or
1793:            some related function before a call to `TSLoad()`.
1794: - viewer - binary file viewer, obtained from `PetscViewerBinaryOpen()`

1796:   Level: intermediate

1798:   Note:
1799:   The type is determined by the data in the file, any type set into the `TS` before this call is ignored.

1801: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerBinaryOpen()`, `TSView()`, `MatLoad()`, `VecLoad()`
1802: @*/
1803: PetscErrorCode TSLoad(TS ts, PetscViewer viewer)
1804: {
1805:   PetscBool isbinary;
1806:   PetscInt  classid;
1807:   char      type[256];
1808:   DMTS      sdm;
1809:   DM        dm;

1811:   PetscFunctionBegin;
1814:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1815:   PetscCheck(isbinary, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid viewer; open viewer with PetscViewerBinaryOpen()");

1817:   PetscCall(PetscViewerBinaryRead(viewer, &classid, 1, NULL, PETSC_INT));
1818:   PetscCheck(classid == TS_FILE_CLASSID, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Not TS next in file");
1819:   PetscCall(PetscViewerBinaryRead(viewer, type, 256, NULL, PETSC_CHAR));
1820:   PetscCall(TSSetType(ts, type));
1821:   PetscTryTypeMethod(ts, load, viewer);
1822:   PetscCall(DMCreate(PetscObjectComm((PetscObject)ts), &dm));
1823:   PetscCall(DMLoad(dm, viewer));
1824:   PetscCall(TSSetDM(ts, dm));
1825:   PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
1826:   PetscCall(VecLoad(ts->vec_sol, viewer));
1827:   PetscCall(DMGetDMTS(ts->dm, &sdm));
1828:   PetscCall(DMTSLoad(sdm, viewer));
1829:   PetscFunctionReturn(PETSC_SUCCESS);
1830: }

1832: #include <petscdraw.h>
1833: #if defined(PETSC_HAVE_SAWS)
1834: #include <petscviewersaws.h>
1835: #endif

1837: /*@
1838:   TSViewFromOptions - View a `TS` based on values in the options database

1840:   Collective

1842:   Input Parameters:
1843: + ts   - the `TS` context
1844: . obj  - Optional object that provides the prefix for the options database keys
1845: - name - command line option string to be passed by user

1847:   Level: intermediate

1849: .seealso: [](ch_ts), `TS`, `TSView`, `PetscObjectViewFromOptions()`, `TSCreate()`
1850: @*/
1851: PetscErrorCode TSViewFromOptions(TS ts, PetscObject obj, const char name[])
1852: {
1853:   PetscFunctionBegin;
1855:   PetscCall(PetscObjectViewFromOptions((PetscObject)ts, obj, name));
1856:   PetscFunctionReturn(PETSC_SUCCESS);
1857: }

1859: /*@
1860:   TSView - Prints the `TS` data structure.

1862:   Collective

1864:   Input Parameters:
1865: + ts     - the `TS` context obtained from `TSCreate()`
1866: - viewer - visualization context

1868:   Options Database Key:
1869: . -ts_view - calls `TSView()` at end of `TSStep()`

1871:   Level: beginner

1873:   Notes:
1874:   The available visualization contexts include
1875: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
1876: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
1877:   output where only the first processor opens
1878:   the file.  All other processors send their
1879:   data to the first processor to print.

1881:   The user can open an alternative visualization context with
1882:   `PetscViewerASCIIOpen()` - output to a specified file.

1884:   In the debugger you can do call `TSView`(ts,0) to display the `TS` solver. (The same holds for any PETSc object viewer).

1886: .seealso: [](ch_ts), `TS`, `PetscViewer`, `PetscViewerASCIIOpen()`
1887: @*/
1888: PetscErrorCode TSView(TS ts, PetscViewer viewer)
1889: {
1890:   TSType    type;
1891:   PetscBool iascii, isstring, isundials, isbinary, isdraw;
1892:   DMTS      sdm;
1893: #if defined(PETSC_HAVE_SAWS)
1894:   PetscBool issaws;
1895: #endif

1897:   PetscFunctionBegin;
1899:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ts), &viewer));
1901:   PetscCheckSameComm(ts, 1, viewer, 2);

1903:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
1904:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
1905:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
1906:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
1907: #if defined(PETSC_HAVE_SAWS)
1908:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSAWS, &issaws));
1909: #endif
1910:   if (iascii) {
1911:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)ts, viewer));
1912:     if (ts->ops->view) {
1913:       PetscCall(PetscViewerASCIIPushTab(viewer));
1914:       PetscUseTypeMethod(ts, view, viewer);
1915:       PetscCall(PetscViewerASCIIPopTab(viewer));
1916:     }
1917:     if (ts->max_steps < PETSC_INT_MAX) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum steps=%" PetscInt_FMT "\n", ts->max_steps));
1918:     if (ts->max_time < PETSC_MAX_REAL) PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum time=%g\n", (double)ts->max_time));
1919:     if (ts->ifuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I function evaluations=%" PetscInt_FMT "\n", ts->ifuncs));
1920:     if (ts->ijacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of I Jacobian evaluations=%" PetscInt_FMT "\n", ts->ijacs));
1921:     if (ts->rhsfuncs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS function evaluations=%" PetscInt_FMT "\n", ts->rhsfuncs));
1922:     if (ts->rhsjacs) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of RHS Jacobian evaluations=%" PetscInt_FMT "\n", ts->rhsjacs));
1923:     if (ts->usessnes) {
1924:       PetscBool lin;
1925:       if (ts->problem_type == TS_NONLINEAR) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of nonlinear solver iterations=%" PetscInt_FMT "\n", ts->snes_its));
1926:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of linear solver iterations=%" PetscInt_FMT "\n", ts->ksp_its));
1927:       PetscCall(PetscObjectTypeCompareAny((PetscObject)ts->snes, &lin, SNESKSPONLY, SNESKSPTRANSPOSEONLY, ""));
1928:       PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of %slinear solve failures=%" PetscInt_FMT "\n", lin ? "" : "non", ts->num_snes_failures));
1929:     }
1930:     PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of rejected steps=%" PetscInt_FMT "\n", ts->reject));
1931:     if (ts->vrtol) PetscCall(PetscViewerASCIIPrintf(viewer, "  using vector of relative error tolerances, "));
1932:     else PetscCall(PetscViewerASCIIPrintf(viewer, "  using relative error tolerance of %g, ", (double)ts->rtol));
1933:     if (ts->vatol) PetscCall(PetscViewerASCIIPrintf(viewer, "  using vector of absolute error tolerances\n"));
1934:     else PetscCall(PetscViewerASCIIPrintf(viewer, "  using absolute error tolerance of %g\n", (double)ts->atol));
1935:     PetscCall(PetscViewerASCIIPushTab(viewer));
1936:     PetscCall(TSAdaptView(ts->adapt, viewer));
1937:     PetscCall(PetscViewerASCIIPopTab(viewer));
1938:   } else if (isstring) {
1939:     PetscCall(TSGetType(ts, &type));
1940:     PetscCall(PetscViewerStringSPrintf(viewer, " TSType: %-7.7s", type));
1941:     PetscTryTypeMethod(ts, view, viewer);
1942:   } else if (isbinary) {
1943:     PetscInt    classid = TS_FILE_CLASSID;
1944:     MPI_Comm    comm;
1945:     PetscMPIInt rank;
1946:     char        type[256];

1948:     PetscCall(PetscObjectGetComm((PetscObject)ts, &comm));
1949:     PetscCallMPI(MPI_Comm_rank(comm, &rank));
1950:     if (rank == 0) {
1951:       PetscCall(PetscViewerBinaryWrite(viewer, &classid, 1, PETSC_INT));
1952:       PetscCall(PetscStrncpy(type, ((PetscObject)ts)->type_name, 256));
1953:       PetscCall(PetscViewerBinaryWrite(viewer, type, 256, PETSC_CHAR));
1954:     }
1955:     PetscTryTypeMethod(ts, view, viewer);
1956:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
1957:     PetscCall(DMView(ts->dm, viewer));
1958:     PetscCall(VecView(ts->vec_sol, viewer));
1959:     PetscCall(DMGetDMTS(ts->dm, &sdm));
1960:     PetscCall(DMTSView(sdm, viewer));
1961:   } else if (isdraw) {
1962:     PetscDraw draw;
1963:     char      str[36];
1964:     PetscReal x, y, bottom, h;

1966:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
1967:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
1968:     PetscCall(PetscStrncpy(str, "TS: ", sizeof(str)));
1969:     PetscCall(PetscStrlcat(str, ((PetscObject)ts)->type_name, sizeof(str)));
1970:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_BLACK, PETSC_DRAW_BLACK, str, NULL, &h));
1971:     bottom = y - h;
1972:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
1973:     PetscTryTypeMethod(ts, view, viewer);
1974:     if (ts->adapt) PetscCall(TSAdaptView(ts->adapt, viewer));
1975:     if (ts->snes) PetscCall(SNESView(ts->snes, viewer));
1976:     PetscCall(PetscDrawPopCurrentPoint(draw));
1977: #if defined(PETSC_HAVE_SAWS)
1978:   } else if (issaws) {
1979:     PetscMPIInt rank;
1980:     const char *name;

1982:     PetscCall(PetscObjectGetName((PetscObject)ts, &name));
1983:     PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
1984:     if (!((PetscObject)ts)->amsmem && rank == 0) {
1985:       char dir[1024];

1987:       PetscCall(PetscObjectViewSAWs((PetscObject)ts, viewer));
1988:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time_step", name));
1989:       PetscCallSAWs(SAWs_Register, (dir, &ts->steps, 1, SAWs_READ, SAWs_INT));
1990:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/time", name));
1991:       PetscCallSAWs(SAWs_Register, (dir, &ts->ptime, 1, SAWs_READ, SAWs_DOUBLE));
1992:     }
1993:     PetscTryTypeMethod(ts, view, viewer);
1994: #endif
1995:   }
1996:   if (ts->snes && ts->usessnes) {
1997:     PetscCall(PetscViewerASCIIPushTab(viewer));
1998:     PetscCall(SNESView(ts->snes, viewer));
1999:     PetscCall(PetscViewerASCIIPopTab(viewer));
2000:   }
2001:   PetscCall(DMGetDMTS(ts->dm, &sdm));
2002:   PetscCall(DMTSView(sdm, viewer));

2004:   PetscCall(PetscViewerASCIIPushTab(viewer));
2005:   PetscCall(PetscObjectTypeCompare((PetscObject)ts, TSSUNDIALS, &isundials));
2006:   PetscCall(PetscViewerASCIIPopTab(viewer));
2007:   PetscFunctionReturn(PETSC_SUCCESS);
2008: }

2010: /*@
2011:   TSSetApplicationContext - Sets an optional user-defined context for the timesteppers that may be accessed, for example inside the user provided
2012:   `TS` callbacks with `TSGetApplicationContext()`

2014:   Logically Collective

2016:   Input Parameters:
2017: + ts  - the `TS` context obtained from `TSCreate()`
2018: - ctx - user context

2020:   Level: intermediate

2022:   Fortran Note:
2023:   This only works when `ctx` is a Fortran derived type (it cannot be a `PetscObject`), we recommend writing a Fortran interface definition for this
2024:   function that tells the Fortran compiler the derived data type that is passed in as the `ctx` argument. See `TSGetApplicationContext()` for
2025:   an example.

2027: .seealso: [](ch_ts), `TS`, `TSGetApplicationContext()`
2028: @*/
2029: PetscErrorCode TSSetApplicationContext(TS ts, PeCtx ctx)
2030: {
2031:   PetscFunctionBegin;
2033:   ts->ctx = ctx;
2034:   PetscFunctionReturn(PETSC_SUCCESS);
2035: }

2037: /*@
2038:   TSGetApplicationContext - Gets the user-defined context for the
2039:   timestepper that was set with `TSSetApplicationContext()`

2041:   Not Collective

2043:   Input Parameter:
2044: . ts - the `TS` context obtained from `TSCreate()`

2046:   Output Parameter:
2047: . ctx - a pointer to the user context

2049:   Level: intermediate

2051:   Fortran Notes:
2052:   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
2053:   function that tells the Fortran compiler the derived data type that is returned as the `ctx` argument. For example,
2054: .vb
2055:   Interface TSGetApplicationContext
2056:     Subroutine TSGetApplicationContext(ts,ctx,ierr)
2057:   #include <petsc/finclude/petscts.h>
2058:       use petscts
2059:       TS ts
2060:       type(tUsertype), pointer :: ctx
2061:       PetscErrorCode ierr
2062:     End Subroutine
2063:   End Interface TSGetApplicationContext
2064: .ve

2066:   The prototype for `ctx` must be
2067: .vb
2068:   type(tUsertype), pointer :: ctx
2069: .ve

2071: .seealso: [](ch_ts), `TS`, `TSSetApplicationContext()`
2072: @*/
2073: PetscErrorCode TSGetApplicationContext(TS ts, void *ctx)
2074: {
2075:   PetscFunctionBegin;
2077:   *(void **)ctx = ts->ctx;
2078:   PetscFunctionReturn(PETSC_SUCCESS);
2079: }

2081: /*@
2082:   TSGetStepNumber - Gets the number of time steps completed.

2084:   Not Collective

2086:   Input Parameter:
2087: . ts - the `TS` context obtained from `TSCreate()`

2089:   Output Parameter:
2090: . steps - number of steps completed so far

2092:   Level: intermediate

2094: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetTimeStep()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`
2095: @*/
2096: PetscErrorCode TSGetStepNumber(TS ts, PetscInt *steps)
2097: {
2098:   PetscFunctionBegin;
2100:   PetscAssertPointer(steps, 2);
2101:   *steps = ts->steps;
2102:   PetscFunctionReturn(PETSC_SUCCESS);
2103: }

2105: /*@
2106:   TSSetStepNumber - Sets the number of steps completed.

2108:   Logically Collective

2110:   Input Parameters:
2111: + ts    - the `TS` context
2112: - steps - number of steps completed so far

2114:   Level: developer

2116:   Note:
2117:   For most uses of the `TS` solvers the user need not explicitly call
2118:   `TSSetStepNumber()`, as the step counter is appropriately updated in
2119:   `TSSolve()`/`TSStep()`/`TSRollBack()`. Power users may call this routine to
2120:   reinitialize timestepping by setting the step counter to zero (and time
2121:   to the initial time) to solve a similar problem with different initial
2122:   conditions or parameters. Other possible use case is to continue
2123:   timestepping from a previously interrupted run in such a way that `TS`
2124:   monitors will be called with a initial nonzero step counter.

2126: .seealso: [](ch_ts), `TS`, `TSGetStepNumber()`, `TSSetTime()`, `TSSetTimeStep()`, `TSSetSolution()`
2127: @*/
2128: PetscErrorCode TSSetStepNumber(TS ts, PetscInt steps)
2129: {
2130:   PetscFunctionBegin;
2133:   PetscCheck(steps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Step number must be non-negative");
2134:   ts->steps = steps;
2135:   PetscFunctionReturn(PETSC_SUCCESS);
2136: }

2138: /*@
2139:   TSSetTimeStep - Allows one to reset the timestep at any time,
2140:   useful for simple pseudo-timestepping codes.

2142:   Logically Collective

2144:   Input Parameters:
2145: + ts        - the `TS` context obtained from `TSCreate()`
2146: - time_step - the size of the timestep

2148:   Level: intermediate

2150: .seealso: [](ch_ts), `TS`, `TSPSEUDO`, `TSGetTimeStep()`, `TSSetTime()`
2151: @*/
2152: PetscErrorCode TSSetTimeStep(TS ts, PetscReal time_step)
2153: {
2154:   PetscFunctionBegin;
2157:   ts->time_step = time_step;
2158:   PetscFunctionReturn(PETSC_SUCCESS);
2159: }

2161: /*@
2162:   TSSetExactFinalTime - Determines whether to adapt the final time step to
2163:   match the exact final time, to interpolate the solution to the exact final time,
2164:   or to just return at the final time `TS` computed (which may be slightly larger
2165:   than the requested final time).

2167:   Logically Collective

2169:   Input Parameters:
2170: + ts     - the time-step context
2171: - eftopt - exact final time option
2172: .vb
2173:   TS_EXACTFINALTIME_STEPOVER    - Don't do anything if final time is exceeded, just use it
2174:   TS_EXACTFINALTIME_INTERPOLATE - Interpolate back to final time if the final time is exceeded
2175:   TS_EXACTFINALTIME_MATCHSTEP   - Adapt final time step to ensure the computed final time exactly equals the requested final time
2176: .ve

2178:   Options Database Key:
2179: . -ts_exact_final_time <stepover,interpolate,matchstep> - select the final step approach at runtime

2181:   Level: beginner

2183:   Note:
2184:   If you use the option `TS_EXACTFINALTIME_STEPOVER` the solution may be at a very different time
2185:   then the final time you selected.

2187: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSGetExactFinalTime()`
2188: @*/
2189: PetscErrorCode TSSetExactFinalTime(TS ts, TSExactFinalTimeOption eftopt)
2190: {
2191:   PetscFunctionBegin;
2194:   ts->exact_final_time = eftopt;
2195:   PetscFunctionReturn(PETSC_SUCCESS);
2196: }

2198: /*@
2199:   TSGetExactFinalTime - Gets the exact final time option set with `TSSetExactFinalTime()`

2201:   Not Collective

2203:   Input Parameter:
2204: . ts - the `TS` context

2206:   Output Parameter:
2207: . eftopt - exact final time option

2209:   Level: beginner

2211: .seealso: [](ch_ts), `TS`, `TSExactFinalTimeOption`, `TSSetExactFinalTime()`
2212: @*/
2213: PetscErrorCode TSGetExactFinalTime(TS ts, TSExactFinalTimeOption *eftopt)
2214: {
2215:   PetscFunctionBegin;
2217:   PetscAssertPointer(eftopt, 2);
2218:   *eftopt = ts->exact_final_time;
2219:   PetscFunctionReturn(PETSC_SUCCESS);
2220: }

2222: /*@
2223:   TSGetTimeStep - Gets the current timestep size.

2225:   Not Collective

2227:   Input Parameter:
2228: . ts - the `TS` context obtained from `TSCreate()`

2230:   Output Parameter:
2231: . dt - the current timestep size

2233:   Level: intermediate

2235: .seealso: [](ch_ts), `TS`, `TSSetTimeStep()`, `TSGetTime()`
2236: @*/
2237: PetscErrorCode TSGetTimeStep(TS ts, PetscReal *dt)
2238: {
2239:   PetscFunctionBegin;
2241:   PetscAssertPointer(dt, 2);
2242:   *dt = ts->time_step;
2243:   PetscFunctionReturn(PETSC_SUCCESS);
2244: }

2246: /*@
2247:   TSGetSolution - Returns the solution at the present timestep. It
2248:   is valid to call this routine inside the function that you are evaluating
2249:   in order to move to the new timestep. This vector not changed until
2250:   the solution at the next timestep has been calculated.

2252:   Not Collective, but v returned is parallel if ts is parallel

2254:   Input Parameter:
2255: . ts - the `TS` context obtained from `TSCreate()`

2257:   Output Parameter:
2258: . v - the vector containing the solution

2260:   Level: intermediate

2262:   Note:
2263:   If you used `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`); this does not return the solution at the requested
2264:   final time. It returns the solution at the next timestep.

2266: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetSolutionComponents()`, `TSSetSolutionFunction()`
2267: @*/
2268: PetscErrorCode TSGetSolution(TS ts, Vec *v)
2269: {
2270:   PetscFunctionBegin;
2272:   PetscAssertPointer(v, 2);
2273:   *v = ts->vec_sol;
2274:   PetscFunctionReturn(PETSC_SUCCESS);
2275: }

2277: /*@
2278:   TSGetSolutionComponents - Returns any solution components at the present
2279:   timestep, if available for the time integration method being used.
2280:   Solution components are quantities that share the same size and
2281:   structure as the solution vector.

2283:   Not Collective, but v returned is parallel if ts is parallel

2285:   Input Parameters:
2286: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2287: . n  - If v is `NULL`, then the number of solution components is
2288:        returned through n, else the n-th solution component is
2289:        returned in v.
2290: - v  - the vector containing the n-th solution component
2291:        (may be `NULL` to use this function to find out
2292:         the number of solutions components).

2294:   Level: advanced

2296: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2297: @*/
2298: PetscErrorCode TSGetSolutionComponents(TS ts, PetscInt *n, Vec *v)
2299: {
2300:   PetscFunctionBegin;
2302:   if (!ts->ops->getsolutioncomponents) *n = 0;
2303:   else PetscUseTypeMethod(ts, getsolutioncomponents, n, v);
2304:   PetscFunctionReturn(PETSC_SUCCESS);
2305: }

2307: /*@
2308:   TSGetAuxSolution - Returns an auxiliary solution at the present
2309:   timestep, if available for the time integration method being used.

2311:   Not Collective, but v returned is parallel if ts is parallel

2313:   Input Parameters:
2314: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2315: - v  - the vector containing the auxiliary solution

2317:   Level: intermediate

2319: .seealso: [](ch_ts), `TS`, `TSGetSolution()`
2320: @*/
2321: PetscErrorCode TSGetAuxSolution(TS ts, Vec *v)
2322: {
2323:   PetscFunctionBegin;
2325:   if (ts->ops->getauxsolution) PetscUseTypeMethod(ts, getauxsolution, v);
2326:   else PetscCall(VecZeroEntries(*v));
2327:   PetscFunctionReturn(PETSC_SUCCESS);
2328: }

2330: /*@
2331:   TSGetTimeError - Returns the estimated error vector, if the chosen
2332:   `TSType` has an error estimation functionality and `TSSetTimeError()` was called

2334:   Not Collective, but v returned is parallel if ts is parallel

2336:   Input Parameters:
2337: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2338: . n  - current estimate (n=0) or previous one (n=-1)
2339: - v  - the vector containing the error (same size as the solution).

2341:   Level: intermediate

2343:   Note:
2344:   MUST call after `TSSetUp()`

2346: .seealso: [](ch_ts), `TSGetSolution()`, `TSSetTimeError()`
2347: @*/
2348: PetscErrorCode TSGetTimeError(TS ts, PetscInt n, Vec *v)
2349: {
2350:   PetscFunctionBegin;
2352:   if (ts->ops->gettimeerror) PetscUseTypeMethod(ts, gettimeerror, n, v);
2353:   else PetscCall(VecZeroEntries(*v));
2354:   PetscFunctionReturn(PETSC_SUCCESS);
2355: }

2357: /*@
2358:   TSSetTimeError - Sets the estimated error vector, if the chosen
2359:   `TSType` has an error estimation functionality. This can be used
2360:   to restart such a time integrator with a given error vector.

2362:   Not Collective, but v returned is parallel if ts is parallel

2364:   Input Parameters:
2365: + ts - the `TS` context obtained from `TSCreate()` (input parameter).
2366: - v  - the vector containing the error (same size as the solution).

2368:   Level: intermediate

2370: .seealso: [](ch_ts), `TS`, `TSSetSolution()`, `TSGetTimeError()`
2371: @*/
2372: PetscErrorCode TSSetTimeError(TS ts, Vec v)
2373: {
2374:   PetscFunctionBegin;
2376:   PetscCheck(ts->setupcalled, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetUp() first");
2377:   PetscTryTypeMethod(ts, settimeerror, v);
2378:   PetscFunctionReturn(PETSC_SUCCESS);
2379: }

2381: /* ----- Routines to initialize and destroy a timestepper ---- */
2382: /*@
2383:   TSSetProblemType - Sets the type of problem to be solved.

2385:   Not collective

2387:   Input Parameters:
2388: + ts   - The `TS`
2389: - type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2390: .vb
2391:          U_t - A U = 0      (linear)
2392:          U_t - A(t) U = 0   (linear)
2393:          F(t,U,U_t) = 0     (nonlinear)
2394: .ve

2396:   Level: beginner

2398: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2399: @*/
2400: PetscErrorCode TSSetProblemType(TS ts, TSProblemType type)
2401: {
2402:   PetscFunctionBegin;
2404:   ts->problem_type = type;
2405:   if (type == TS_LINEAR) {
2406:     SNES snes;
2407:     PetscCall(TSGetSNES(ts, &snes));
2408:     PetscCall(SNESSetType(snes, SNESKSPONLY));
2409:   }
2410:   PetscFunctionReturn(PETSC_SUCCESS);
2411: }

2413: /*@
2414:   TSGetProblemType - Gets the type of problem to be solved.

2416:   Not collective

2418:   Input Parameter:
2419: . ts - The `TS`

2421:   Output Parameter:
2422: . type - One of `TS_LINEAR`, `TS_NONLINEAR` where these types refer to problems of the forms
2423: .vb
2424:          M U_t = A U
2425:          M(t) U_t = A(t) U
2426:          F(t,U,U_t)
2427: .ve

2429:   Level: beginner

2431: .seealso: [](ch_ts), `TSSetUp()`, `TSProblemType`, `TS`
2432: @*/
2433: PetscErrorCode TSGetProblemType(TS ts, TSProblemType *type)
2434: {
2435:   PetscFunctionBegin;
2437:   PetscAssertPointer(type, 2);
2438:   *type = ts->problem_type;
2439:   PetscFunctionReturn(PETSC_SUCCESS);
2440: }

2442: /*
2443:     Attempt to check/preset a default value for the exact final time option. This is needed at the beginning of TSSolve() and in TSSetUp()
2444: */
2445: static PetscErrorCode TSSetExactFinalTimeDefault(TS ts)
2446: {
2447:   PetscBool isnone;

2449:   PetscFunctionBegin;
2450:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2451:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2453:   PetscCall(PetscObjectTypeCompare((PetscObject)ts->adapt, TSADAPTNONE, &isnone));
2454:   if (!isnone && ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_MATCHSTEP;
2455:   else if (ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED) ts->exact_final_time = TS_EXACTFINALTIME_INTERPOLATE;
2456:   PetscFunctionReturn(PETSC_SUCCESS);
2457: }

2459: /*@
2460:   TSSetUp - Sets up the internal data structures for the later use of a timestepper.

2462:   Collective

2464:   Input Parameter:
2465: . ts - the `TS` context obtained from `TSCreate()`

2467:   Level: advanced

2469:   Note:
2470:   For basic use of the `TS` solvers the user need not explicitly call
2471:   `TSSetUp()`, since these actions will automatically occur during
2472:   the call to `TSStep()` or `TSSolve()`.  However, if one wishes to control this
2473:   phase separately, `TSSetUp()` should be called after `TSCreate()`
2474:   and optional routines of the form TSSetXXX(), but before `TSStep()` and `TSSolve()`.

2476: .seealso: [](ch_ts), `TSCreate()`, `TS`, `TSStep()`, `TSDestroy()`, `TSSolve()`
2477: @*/
2478: PetscErrorCode TSSetUp(TS ts)
2479: {
2480:   DM dm;
2481:   PetscErrorCode (*func)(SNES, Vec, Vec, void *);
2482:   PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *);
2483:   TSIFunctionFn   *ifun;
2484:   TSIJacobianFn   *ijac;
2485:   TSI2JacobianFn  *i2jac;
2486:   TSRHSJacobianFn *rhsjac;

2488:   PetscFunctionBegin;
2490:   if (ts->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);

2492:   if (!((PetscObject)ts)->type_name) {
2493:     PetscCall(TSGetIFunction(ts, NULL, &ifun, NULL));
2494:     PetscCall(TSSetType(ts, ifun ? TSBEULER : TSEULER));
2495:   }

2497:   if (!ts->vec_sol) {
2498:     PetscCheck(ts->dm, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call TSSetSolution() first");
2499:     PetscCall(DMCreateGlobalVector(ts->dm, &ts->vec_sol));
2500:   }

2502:   if (ts->eval_times) {
2503:     if (!ts->eval_times->sol_vecs) PetscCall(VecDuplicateVecs(ts->vec_sol, ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
2504:     if (!ts->eval_times->sol_times) PetscCall(PetscMalloc1(ts->eval_times->num_time_points, &ts->eval_times->sol_times));
2505:   }
2506:   if (!ts->Jacp && ts->Jacprhs) { /* IJacobianP shares the same matrix with RHSJacobianP if only RHSJacobianP is provided */
2507:     PetscCall(PetscObjectReference((PetscObject)ts->Jacprhs));
2508:     ts->Jacp = ts->Jacprhs;
2509:   }

2511:   if (ts->quadraturets) {
2512:     PetscCall(TSSetUp(ts->quadraturets));
2513:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2514:     PetscCall(VecDuplicate(ts->quadraturets->vec_sol, &ts->vec_costintegrand));
2515:   }

2517:   PetscCall(TSGetRHSJacobian(ts, NULL, NULL, &rhsjac, NULL));
2518:   if (rhsjac == TSComputeRHSJacobianConstant) {
2519:     Mat  Amat, Pmat;
2520:     SNES snes;
2521:     PetscCall(TSGetSNES(ts, &snes));
2522:     PetscCall(SNESGetJacobian(snes, &Amat, &Pmat, NULL, NULL));
2523:     /* Matching matrices implies that an IJacobian is NOT set, because if it had been set, the IJacobian's matrix would
2524:      * have displaced the RHS matrix */
2525:     if (Amat && Amat == ts->Arhs) {
2526:       /* 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 */
2527:       PetscCall(MatDuplicate(ts->Arhs, MAT_COPY_VALUES, &Amat));
2528:       PetscCall(SNESSetJacobian(snes, Amat, NULL, NULL, NULL));
2529:       PetscCall(MatDestroy(&Amat));
2530:     }
2531:     if (Pmat && Pmat == ts->Brhs) {
2532:       PetscCall(MatDuplicate(ts->Brhs, MAT_COPY_VALUES, &Pmat));
2533:       PetscCall(SNESSetJacobian(snes, NULL, Pmat, NULL, NULL));
2534:       PetscCall(MatDestroy(&Pmat));
2535:     }
2536:   }

2538:   PetscCall(TSGetAdapt(ts, &ts->adapt));
2539:   PetscCall(TSAdaptSetDefaultType(ts->adapt, ts->default_adapt_type));

2541:   PetscTryTypeMethod(ts, setup);

2543:   PetscCall(TSSetExactFinalTimeDefault(ts));

2545:   /* In the case where we've set a DMTSFunction or what have you, we need the default SNESFunction
2546:      to be set right but can't do it elsewhere due to the overreliance on ctx=ts.
2547:    */
2548:   PetscCall(TSGetDM(ts, &dm));
2549:   PetscCall(DMSNESGetFunction(dm, &func, NULL));
2550:   if (!func) PetscCall(DMSNESSetFunction(dm, SNESTSFormFunction, ts));

2552:   /* If the SNES doesn't have a jacobian set and the TS has an ijacobian or rhsjacobian set, set the SNES to use it.
2553:      Otherwise, the SNES will use coloring internally to form the Jacobian.
2554:    */
2555:   PetscCall(DMSNESGetJacobian(dm, &jac, NULL));
2556:   PetscCall(DMTSGetIJacobian(dm, &ijac, NULL));
2557:   PetscCall(DMTSGetI2Jacobian(dm, &i2jac, NULL));
2558:   PetscCall(DMTSGetRHSJacobian(dm, &rhsjac, NULL));
2559:   if (!jac && (ijac || i2jac || rhsjac)) PetscCall(DMSNESSetJacobian(dm, SNESTSFormJacobian, ts));

2561:   /* if time integration scheme has a starting method, call it */
2562:   PetscTryTypeMethod(ts, startingmethod);

2564:   ts->setupcalled = PETSC_TRUE;
2565:   PetscFunctionReturn(PETSC_SUCCESS);
2566: }

2568: /*@
2569:   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

2571:   Collective

2573:   Input Parameter:
2574: . ts - the `TS` context obtained from `TSCreate()`

2576:   Level: developer

2578:   Notes:
2579:   Any options set on the `TS` object, including those set with `TSSetFromOptions()` remain.

2581:   See also `TSSetResize()` to change the size of the system being integrated (for example by adaptive mesh refinement) during the time integration.

2583: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSetResize()`
2584: @*/
2585: PetscErrorCode TSReset(TS ts)
2586: {
2587:   TS_RHSSplitLink ilink = ts->tsrhssplit, next;

2589:   PetscFunctionBegin;

2592:   PetscTryTypeMethod(ts, reset);
2593:   if (ts->snes) PetscCall(SNESReset(ts->snes));
2594:   if (ts->adapt) PetscCall(TSAdaptReset(ts->adapt));

2596:   PetscCall(MatDestroy(&ts->Arhs));
2597:   PetscCall(MatDestroy(&ts->Brhs));
2598:   PetscCall(VecDestroy(&ts->Frhs));
2599:   PetscCall(VecDestroy(&ts->vec_sol));
2600:   PetscCall(VecDestroy(&ts->vec_sol0));
2601:   PetscCall(VecDestroy(&ts->vec_dot));
2602:   PetscCall(VecDestroy(&ts->vatol));
2603:   PetscCall(VecDestroy(&ts->vrtol));
2604:   PetscCall(VecDestroyVecs(ts->nwork, &ts->work));

2606:   PetscCall(MatDestroy(&ts->Jacprhs));
2607:   PetscCall(MatDestroy(&ts->Jacp));
2608:   if (ts->forward_solve) PetscCall(TSForwardReset(ts));
2609:   if (ts->quadraturets) {
2610:     PetscCall(TSReset(ts->quadraturets));
2611:     PetscCall(VecDestroy(&ts->vec_costintegrand));
2612:   }
2613:   while (ilink) {
2614:     next = ilink->next;
2615:     PetscCall(TSDestroy(&ilink->ts));
2616:     PetscCall(PetscFree(ilink->splitname));
2617:     PetscCall(ISDestroy(&ilink->is));
2618:     PetscCall(PetscFree(ilink));
2619:     ilink = next;
2620:   }
2621:   ts->tsrhssplit     = NULL;
2622:   ts->num_rhs_splits = 0;
2623:   if (ts->eval_times) {
2624:     PetscCall(PetscFree(ts->eval_times->time_points));
2625:     PetscCall(PetscFree(ts->eval_times->sol_times));
2626:     PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
2627:     PetscCall(PetscFree(ts->eval_times));
2628:   }
2629:   ts->rhsjacobian.time  = PETSC_MIN_REAL;
2630:   ts->rhsjacobian.scale = 1.0;
2631:   ts->ijacobian.shift   = 1.0;
2632:   ts->setupcalled       = PETSC_FALSE;
2633:   PetscFunctionReturn(PETSC_SUCCESS);
2634: }

2636: static PetscErrorCode TSResizeReset(TS);

2638: /*@
2639:   TSDestroy - Destroys the timestepper context that was created
2640:   with `TSCreate()`.

2642:   Collective

2644:   Input Parameter:
2645: . ts - the `TS` context obtained from `TSCreate()`

2647:   Level: beginner

2649: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSSolve()`
2650: @*/
2651: PetscErrorCode TSDestroy(TS *ts)
2652: {
2653:   PetscFunctionBegin;
2654:   if (!*ts) PetscFunctionReturn(PETSC_SUCCESS);
2656:   if (--((PetscObject)*ts)->refct > 0) {
2657:     *ts = NULL;
2658:     PetscFunctionReturn(PETSC_SUCCESS);
2659:   }

2661:   PetscCall(TSReset(*ts));
2662:   PetscCall(TSAdjointReset(*ts));
2663:   if ((*ts)->forward_solve) PetscCall(TSForwardReset(*ts));
2664:   PetscCall(TSResizeReset(*ts));

2666:   /* if memory was published with SAWs then destroy it */
2667:   PetscCall(PetscObjectSAWsViewOff((PetscObject)*ts));
2668:   PetscTryTypeMethod(*ts, destroy);

2670:   PetscCall(TSTrajectoryDestroy(&(*ts)->trajectory));

2672:   PetscCall(TSAdaptDestroy(&(*ts)->adapt));
2673:   PetscCall(TSEventDestroy(&(*ts)->event));

2675:   PetscCall(SNESDestroy(&(*ts)->snes));
2676:   PetscCall(SNESDestroy(&(*ts)->snesrhssplit));
2677:   PetscCall(DMDestroy(&(*ts)->dm));
2678:   PetscCall(TSMonitorCancel(*ts));
2679:   PetscCall(TSAdjointMonitorCancel(*ts));

2681:   PetscCall(TSDestroy(&(*ts)->quadraturets));
2682:   PetscCall(PetscHeaderDestroy(ts));
2683:   PetscFunctionReturn(PETSC_SUCCESS);
2684: }

2686: /*@
2687:   TSGetSNES - Returns the `SNES` (nonlinear solver) associated with
2688:   a `TS` (timestepper) context. Valid only for nonlinear problems.

2690:   Not Collective, but snes is parallel if ts is parallel

2692:   Input Parameter:
2693: . ts - the `TS` context obtained from `TSCreate()`

2695:   Output Parameter:
2696: . snes - the nonlinear solver context

2698:   Level: beginner

2700:   Notes:
2701:   The user can then directly manipulate the `SNES` context to set various
2702:   options, etc.  Likewise, the user can then extract and manipulate the
2703:   `KSP`, and `PC` contexts as well.

2705:   `TSGetSNES()` does not work for integrators that do not use `SNES`; in
2706:   this case `TSGetSNES()` returns `NULL` in `snes`.

2708: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`
2709: @*/
2710: PetscErrorCode TSGetSNES(TS ts, SNES *snes)
2711: {
2712:   PetscFunctionBegin;
2714:   PetscAssertPointer(snes, 2);
2715:   if (!ts->snes) {
2716:     PetscCall(SNESCreate(PetscObjectComm((PetscObject)ts), &ts->snes));
2717:     PetscCall(PetscObjectSetOptions((PetscObject)ts->snes, ((PetscObject)ts)->options));
2718:     PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2719:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->snes, (PetscObject)ts, 1));
2720:     if (ts->dm) PetscCall(SNESSetDM(ts->snes, ts->dm));
2721:     if (ts->problem_type == TS_LINEAR) PetscCall(SNESSetType(ts->snes, SNESKSPONLY));
2722:   }
2723:   *snes = ts->snes;
2724:   PetscFunctionReturn(PETSC_SUCCESS);
2725: }

2727: /*@
2728:   TSSetSNES - Set the `SNES` (nonlinear solver) to be used by the `TS` timestepping context

2730:   Collective

2732:   Input Parameters:
2733: + ts   - the `TS` context obtained from `TSCreate()`
2734: - snes - the nonlinear solver context

2736:   Level: developer

2738:   Note:
2739:   Most users should have the `TS` created by calling `TSGetSNES()`

2741: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetSNES()`
2742: @*/
2743: PetscErrorCode TSSetSNES(TS ts, SNES snes)
2744: {
2745:   PetscErrorCode (*func)(SNES, Vec, Mat, Mat, void *);

2747:   PetscFunctionBegin;
2750:   PetscCall(PetscObjectReference((PetscObject)snes));
2751:   PetscCall(SNESDestroy(&ts->snes));

2753:   ts->snes = snes;

2755:   PetscCall(SNESSetFunction(ts->snes, NULL, SNESTSFormFunction, ts));
2756:   PetscCall(SNESGetJacobian(ts->snes, NULL, NULL, &func, NULL));
2757:   if (func == SNESTSFormJacobian) PetscCall(SNESSetJacobian(ts->snes, NULL, NULL, SNESTSFormJacobian, ts));
2758:   PetscFunctionReturn(PETSC_SUCCESS);
2759: }

2761: /*@
2762:   TSGetKSP - Returns the `KSP` (linear solver) associated with
2763:   a `TS` (timestepper) context.

2765:   Not Collective, but `ksp` is parallel if `ts` is parallel

2767:   Input Parameter:
2768: . ts - the `TS` context obtained from `TSCreate()`

2770:   Output Parameter:
2771: . ksp - the nonlinear solver context

2773:   Level: beginner

2775:   Notes:
2776:   The user can then directly manipulate the `KSP` context to set various
2777:   options, etc.  Likewise, the user can then extract and manipulate the
2778:   `PC` context as well.

2780:   `TSGetKSP()` does not work for integrators that do not use `KSP`;
2781:   in this case `TSGetKSP()` returns `NULL` in `ksp`.

2783: .seealso: [](ch_ts), `TS`, `SNES`, `KSP`, `TSCreate()`, `TSSetUp()`, `TSSolve()`, `TSGetSNES()`
2784: @*/
2785: PetscErrorCode TSGetKSP(TS ts, KSP *ksp)
2786: {
2787:   SNES snes;

2789:   PetscFunctionBegin;
2791:   PetscAssertPointer(ksp, 2);
2792:   PetscCheck(((PetscObject)ts)->type_name, PETSC_COMM_SELF, PETSC_ERR_ARG_NULL, "KSP is not created yet. Call TSSetType() first");
2793:   PetscCheck(ts->problem_type == TS_LINEAR, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Linear only; use TSGetSNES()");
2794:   PetscCall(TSGetSNES(ts, &snes));
2795:   PetscCall(SNESGetKSP(snes, ksp));
2796:   PetscFunctionReturn(PETSC_SUCCESS);
2797: }

2799: /* ----------- Routines to set solver parameters ---------- */

2801: /*@
2802:   TSSetMaxSteps - Sets the maximum number of steps to use.

2804:   Logically Collective

2806:   Input Parameters:
2807: + ts       - the `TS` context obtained from `TSCreate()`
2808: - maxsteps - maximum number of steps to use

2810:   Options Database Key:
2811: . -ts_max_steps <maxsteps> - Sets maxsteps

2813:   Level: intermediate

2815:   Note:
2816:   Use `PETSC_DETERMINE` to reset the maximum number of steps to the default from when the object's type was set

2818:   The default maximum number of steps is 5,000

2820:   Fortran Note:
2821:   Use `PETSC_DETERMINE_INTEGER`

2823: .seealso: [](ch_ts), `TS`, `TSGetMaxSteps()`, `TSSetMaxTime()`, `TSSetExactFinalTime()`
2824: @*/
2825: PetscErrorCode TSSetMaxSteps(TS ts, PetscInt maxsteps)
2826: {
2827:   PetscFunctionBegin;
2830:   if (maxsteps == PETSC_DETERMINE) {
2831:     ts->max_steps = ts->default_max_steps;
2832:   } else {
2833:     PetscCheck(maxsteps >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of steps must be non-negative");
2834:     ts->max_steps = maxsteps;
2835:   }
2836:   PetscFunctionReturn(PETSC_SUCCESS);
2837: }

2839: /*@
2840:   TSGetMaxSteps - Gets the maximum number of steps to use.

2842:   Not Collective

2844:   Input Parameter:
2845: . ts - the `TS` context obtained from `TSCreate()`

2847:   Output Parameter:
2848: . maxsteps - maximum number of steps to use

2850:   Level: advanced

2852: .seealso: [](ch_ts), `TS`, `TSSetMaxSteps()`, `TSGetMaxTime()`, `TSSetMaxTime()`
2853: @*/
2854: PetscErrorCode TSGetMaxSteps(TS ts, PetscInt *maxsteps)
2855: {
2856:   PetscFunctionBegin;
2858:   PetscAssertPointer(maxsteps, 2);
2859:   *maxsteps = ts->max_steps;
2860:   PetscFunctionReturn(PETSC_SUCCESS);
2861: }

2863: /*@
2864:   TSSetMaxTime - Sets the maximum (or final) time for timestepping.

2866:   Logically Collective

2868:   Input Parameters:
2869: + ts      - the `TS` context obtained from `TSCreate()`
2870: - maxtime - final time to step to

2872:   Options Database Key:
2873: . -ts_max_time <maxtime> - Sets maxtime

2875:   Level: intermediate

2877:   Notes:
2878:   Use `PETSC_DETERMINE` to reset the maximum time to the default from when the object's type was set

2880:   The default maximum time is 5.0

2882:   Fortran Note:
2883:   Use `PETSC_DETERMINE_REAL`

2885: .seealso: [](ch_ts), `TS`, `TSGetMaxTime()`, `TSSetMaxSteps()`, `TSSetExactFinalTime()`
2886: @*/
2887: PetscErrorCode TSSetMaxTime(TS ts, PetscReal maxtime)
2888: {
2889:   PetscFunctionBegin;
2892:   if (maxtime == PETSC_DETERMINE) {
2893:     ts->max_time = ts->default_max_time;
2894:   } else {
2895:     ts->max_time = maxtime;
2896:   }
2897:   PetscFunctionReturn(PETSC_SUCCESS);
2898: }

2900: /*@
2901:   TSGetMaxTime - Gets the maximum (or final) time for timestepping.

2903:   Not Collective

2905:   Input Parameter:
2906: . ts - the `TS` context obtained from `TSCreate()`

2908:   Output Parameter:
2909: . maxtime - final time to step to

2911:   Level: advanced

2913: .seealso: [](ch_ts), `TS`, `TSSetMaxTime()`, `TSGetMaxSteps()`, `TSSetMaxSteps()`
2914: @*/
2915: PetscErrorCode TSGetMaxTime(TS ts, PetscReal *maxtime)
2916: {
2917:   PetscFunctionBegin;
2919:   PetscAssertPointer(maxtime, 2);
2920:   *maxtime = ts->max_time;
2921:   PetscFunctionReturn(PETSC_SUCCESS);
2922: }

2924: // PetscClangLinter pragma disable: -fdoc-*
2925: /*@
2926:   TSSetInitialTimeStep - Deprecated, use `TSSetTime()` and `TSSetTimeStep()`.

2928:   Level: deprecated

2930: @*/
2931: PetscErrorCode TSSetInitialTimeStep(TS ts, PetscReal initial_time, PetscReal time_step)
2932: {
2933:   PetscFunctionBegin;
2935:   PetscCall(TSSetTime(ts, initial_time));
2936:   PetscCall(TSSetTimeStep(ts, time_step));
2937:   PetscFunctionReturn(PETSC_SUCCESS);
2938: }

2940: // PetscClangLinter pragma disable: -fdoc-*
2941: /*@
2942:   TSGetDuration - Deprecated, use `TSGetMaxSteps()` and `TSGetMaxTime()`.

2944:   Level: deprecated

2946: @*/
2947: PetscErrorCode TSGetDuration(TS ts, PetscInt *maxsteps, PetscReal *maxtime)
2948: {
2949:   PetscFunctionBegin;
2951:   if (maxsteps) {
2952:     PetscAssertPointer(maxsteps, 2);
2953:     *maxsteps = ts->max_steps;
2954:   }
2955:   if (maxtime) {
2956:     PetscAssertPointer(maxtime, 3);
2957:     *maxtime = ts->max_time;
2958:   }
2959:   PetscFunctionReturn(PETSC_SUCCESS);
2960: }

2962: // PetscClangLinter pragma disable: -fdoc-*
2963: /*@
2964:   TSSetDuration - Deprecated, use `TSSetMaxSteps()` and `TSSetMaxTime()`.

2966:   Level: deprecated

2968: @*/
2969: PetscErrorCode TSSetDuration(TS ts, PetscInt maxsteps, PetscReal maxtime)
2970: {
2971:   PetscFunctionBegin;
2972:   if (maxsteps != PETSC_CURRENT) PetscCall(TSSetMaxSteps(ts, maxsteps));
2973:   if (maxtime != (PetscReal)PETSC_CURRENT) PetscCall(TSSetMaxTime(ts, maxtime));
2974:   PetscFunctionReturn(PETSC_SUCCESS);
2975: }

2977: // PetscClangLinter pragma disable: -fdoc-*
2978: /*@
2979:   TSGetTimeStepNumber - Deprecated, use `TSGetStepNumber()`.

2981:   Level: deprecated

2983: @*/
2984: PetscErrorCode TSGetTimeStepNumber(TS ts, PetscInt *steps)
2985: {
2986:   return TSGetStepNumber(ts, steps);
2987: }

2989: // PetscClangLinter pragma disable: -fdoc-*
2990: /*@
2991:   TSGetTotalSteps - Deprecated, use `TSGetStepNumber()`.

2993:   Level: deprecated

2995: @*/
2996: PetscErrorCode TSGetTotalSteps(TS ts, PetscInt *steps)
2997: {
2998:   return TSGetStepNumber(ts, steps);
2999: }

3001: /*@
3002:   TSSetSolution - Sets the initial solution vector
3003:   for use by the `TS` routines.

3005:   Logically Collective

3007:   Input Parameters:
3008: + ts - the `TS` context obtained from `TSCreate()`
3009: - u  - the solution vector

3011:   Level: beginner

3013: .seealso: [](ch_ts), `TS`, `TSSetSolutionFunction()`, `TSGetSolution()`, `TSCreate()`
3014: @*/
3015: PetscErrorCode TSSetSolution(TS ts, Vec u)
3016: {
3017:   DM dm;

3019:   PetscFunctionBegin;
3022:   PetscCall(PetscObjectReference((PetscObject)u));
3023:   PetscCall(VecDestroy(&ts->vec_sol));
3024:   ts->vec_sol = u;

3026:   PetscCall(TSGetDM(ts, &dm));
3027:   PetscCall(DMShellSetGlobalVector(dm, u));
3028:   PetscFunctionReturn(PETSC_SUCCESS);
3029: }

3031: /*@C
3032:   TSSetPreStep - Sets the general-purpose function
3033:   called once at the beginning of each time step.

3035:   Logically Collective

3037:   Input Parameters:
3038: + ts   - The `TS` context obtained from `TSCreate()`
3039: - func - The function

3041:   Calling sequence of `func`:
3042: . ts - the `TS` context

3044:   Level: intermediate

3046: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPostStage()`, `TSSetPostStep()`, `TSStep()`, `TSRestartStep()`
3047: @*/
3048: PetscErrorCode TSSetPreStep(TS ts, PetscErrorCode (*func)(TS ts))
3049: {
3050:   PetscFunctionBegin;
3052:   ts->prestep = func;
3053:   PetscFunctionReturn(PETSC_SUCCESS);
3054: }

3056: /*@
3057:   TSPreStep - Runs the user-defined pre-step function provided with `TSSetPreStep()`

3059:   Collective

3061:   Input Parameter:
3062: . ts - The `TS` context obtained from `TSCreate()`

3064:   Level: developer

3066:   Note:
3067:   `TSPreStep()` is typically used within time stepping implementations,
3068:   so most users would not generally call this routine themselves.

3070: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSPreStage()`, `TSPostStage()`, `TSPostStep()`
3071: @*/
3072: PetscErrorCode TSPreStep(TS ts)
3073: {
3074:   PetscFunctionBegin;
3076:   if (ts->prestep) {
3077:     Vec              U;
3078:     PetscObjectId    idprev;
3079:     PetscBool        sameObject;
3080:     PetscObjectState sprev, spost;

3082:     PetscCall(TSGetSolution(ts, &U));
3083:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3084:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3085:     PetscCallBack("TS callback preset", (*ts->prestep)(ts));
3086:     PetscCall(TSGetSolution(ts, &U));
3087:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3088:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3089:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3090:   }
3091:   PetscFunctionReturn(PETSC_SUCCESS);
3092: }

3094: /*@C
3095:   TSSetPreStage - Sets the general-purpose function
3096:   called once at the beginning of each stage.

3098:   Logically Collective

3100:   Input Parameters:
3101: + ts   - The `TS` context obtained from `TSCreate()`
3102: - func - The function

3104:   Calling sequence of `func`:
3105: + ts        - the `TS` context
3106: - stagetime - the stage time

3108:   Level: intermediate

3110:   Note:
3111:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3112:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3113:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3115: .seealso: [](ch_ts), `TS`, `TSSetPostStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3116: @*/
3117: PetscErrorCode TSSetPreStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime))
3118: {
3119:   PetscFunctionBegin;
3121:   ts->prestage = func;
3122:   PetscFunctionReturn(PETSC_SUCCESS);
3123: }

3125: /*@C
3126:   TSSetPostStage - Sets the general-purpose function
3127:   called once at the end of each stage.

3129:   Logically Collective

3131:   Input Parameters:
3132: + ts   - The `TS` context obtained from `TSCreate()`
3133: - func - The function

3135:   Calling sequence of `func`:
3136: + ts         - the `TS` context
3137: . stagetime  - the stage time
3138: . stageindex - the stage index
3139: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3141:   Level: intermediate

3143:   Note:
3144:   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
3145:   The time step number being computed can be queried using `TSGetStepNumber()` and the total size of the step being
3146:   attempted can be obtained using `TSGetTimeStep()`. The time at the start of the step is available via `TSGetTime()`.

3148: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3149: @*/
3150: PetscErrorCode TSSetPostStage(TS ts, PetscErrorCode (*func)(TS ts, PetscReal stagetime, PetscInt stageindex, Vec *Y))
3151: {
3152:   PetscFunctionBegin;
3154:   ts->poststage = func;
3155:   PetscFunctionReturn(PETSC_SUCCESS);
3156: }

3158: /*@C
3159:   TSSetPostEvaluate - Sets the general-purpose function
3160:   called at the end of each step evaluation.

3162:   Logically Collective

3164:   Input Parameters:
3165: + ts   - The `TS` context obtained from `TSCreate()`
3166: - func - The function

3168:   Calling sequence of `func`:
3169: . ts - the `TS` context

3171:   Level: intermediate

3173:   Note:
3174:   The function set by `TSSetPostEvaluate()` is called after the solution is evaluated, or after the step rollback.
3175:   Inside the `func` callback, the solution vector can be obtained with `TSGetSolution()`, and modified, if need be.
3176:   The time step can be obtained with `TSGetTimeStep()`, and the time at the start of the step - via `TSGetTime()`.
3177:   The potential changes to the solution vector introduced by event handling (`postevent()`) are not relevant for `TSSetPostEvaluate()`,
3178:   but are relevant for `TSSetPostStep()`, according to the function call scheme in `TSSolve()`, as shown below
3179: .vb
3180:   ...
3181:   Step()
3182:   PostEvaluate()
3183:   EventHandling()
3184:   step_rollback ? PostEvaluate() : PostStep()
3185:   ...
3186: .ve
3187:   where EventHandling() may result in one of the following three outcomes
3188: .vb
3189:   (1) | successful step | solution intact
3190:   (2) | successful step | solution modified by `postevent()`
3191:   (3) | step_rollback   | solution rolled back
3192: .ve

3194: .seealso: [](ch_ts), `TS`, `TSSetPreStage()`, `TSSetPreStep()`, `TSSetPostStep()`, `TSGetApplicationContext()`
3195: @*/
3196: PetscErrorCode TSSetPostEvaluate(TS ts, PetscErrorCode (*func)(TS ts))
3197: {
3198:   PetscFunctionBegin;
3200:   ts->postevaluate = func;
3201:   PetscFunctionReturn(PETSC_SUCCESS);
3202: }

3204: /*@
3205:   TSPreStage - Runs the user-defined pre-stage function set using `TSSetPreStage()`

3207:   Collective

3209:   Input Parameters:
3210: + ts        - The `TS` context obtained from `TSCreate()`
3211: - stagetime - The absolute time of the current stage

3213:   Level: developer

3215:   Note:
3216:   `TSPreStage()` is typically used within time stepping implementations,
3217:   most users would not generally call this routine themselves.

3219: .seealso: [](ch_ts), `TS`, `TSPostStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3220: @*/
3221: PetscErrorCode TSPreStage(TS ts, PetscReal stagetime)
3222: {
3223:   PetscFunctionBegin;
3225:   if (ts->prestage) PetscCallBack("TS callback prestage", (*ts->prestage)(ts, stagetime));
3226:   PetscFunctionReturn(PETSC_SUCCESS);
3227: }

3229: /*@
3230:   TSPostStage - Runs the user-defined post-stage function set using `TSSetPostStage()`

3232:   Collective

3234:   Input Parameters:
3235: + ts         - The `TS` context obtained from `TSCreate()`
3236: . stagetime  - The absolute time of the current stage
3237: . stageindex - Stage number
3238: - Y          - Array of vectors (of size = total number of stages) with the stage solutions

3240:   Level: developer

3242:   Note:
3243:   `TSPostStage()` is typically used within time stepping implementations,
3244:   most users would not generally call this routine themselves.

3246: .seealso: [](ch_ts), `TS`, `TSPreStage()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3247: @*/
3248: PetscErrorCode TSPostStage(TS ts, PetscReal stagetime, PetscInt stageindex, Vec *Y)
3249: {
3250:   PetscFunctionBegin;
3252:   if (ts->poststage) PetscCallBack("TS callback poststage", (*ts->poststage)(ts, stagetime, stageindex, Y));
3253:   PetscFunctionReturn(PETSC_SUCCESS);
3254: }

3256: /*@
3257:   TSPostEvaluate - Runs the user-defined post-evaluate function set using `TSSetPostEvaluate()`

3259:   Collective

3261:   Input Parameter:
3262: . ts - The `TS` context obtained from `TSCreate()`

3264:   Level: developer

3266:   Note:
3267:   `TSPostEvaluate()` is typically used within time stepping implementations,
3268:   most users would not generally call this routine themselves.

3270: .seealso: [](ch_ts), `TS`, `TSSetPostEvaluate()`, `TSSetPreStep()`, `TSPreStep()`, `TSPostStep()`
3271: @*/
3272: PetscErrorCode TSPostEvaluate(TS ts)
3273: {
3274:   PetscFunctionBegin;
3276:   if (ts->postevaluate) {
3277:     Vec              U;
3278:     PetscObjectState sprev, spost;

3280:     PetscCall(TSGetSolution(ts, &U));
3281:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3282:     PetscCallBack("TS callback postevaluate", (*ts->postevaluate)(ts));
3283:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3284:     if (sprev != spost) PetscCall(TSRestartStep(ts));
3285:   }
3286:   PetscFunctionReturn(PETSC_SUCCESS);
3287: }

3289: /*@C
3290:   TSSetPostStep - Sets the general-purpose function
3291:   called once at the end of each successful time step.

3293:   Logically Collective

3295:   Input Parameters:
3296: + ts   - The `TS` context obtained from `TSCreate()`
3297: - func - The function

3299:   Calling sequence of `func`:
3300: . ts - the `TS` context

3302:   Level: intermediate

3304:   Note:
3305:   The function set by `TSSetPostStep()` is called after each successful step. If the event handler locates an event at the
3306:   given step, and `postevent()` modifies the solution vector, the solution vector obtained by `TSGetSolution()` inside `func` will
3307:   contain the changes. To get the solution without these changes, use `TSSetPostEvaluate()` to set the appropriate callback.
3308:   The scheme of the relevant function calls in `TSSolve()` is shown below
3309: .vb
3310:   ...
3311:   Step()
3312:   PostEvaluate()
3313:   EventHandling()
3314:   step_rollback ? PostEvaluate() : PostStep()
3315:   ...
3316: .ve
3317:   where EventHandling() may result in one of the following three outcomes
3318: .vb
3319:   (1) | successful step | solution intact
3320:   (2) | successful step | solution modified by `postevent()`
3321:   (3) | step_rollback   | solution rolled back
3322: .ve

3324: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSRestartStep()`
3325: @*/
3326: PetscErrorCode TSSetPostStep(TS ts, PetscErrorCode (*func)(TS ts))
3327: {
3328:   PetscFunctionBegin;
3330:   ts->poststep = func;
3331:   PetscFunctionReturn(PETSC_SUCCESS);
3332: }

3334: /*@
3335:   TSPostStep - Runs the user-defined post-step function that was set with `TSSetPostStep()`

3337:   Collective

3339:   Input Parameter:
3340: . ts - The `TS` context obtained from `TSCreate()`

3342:   Note:
3343:   `TSPostStep()` is typically used within time stepping implementations,
3344:   so most users would not generally call this routine themselves.

3346:   Level: developer

3348: .seealso: [](ch_ts), `TS`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostEvaluate()`, `TSGetTimeStep()`, `TSGetStepNumber()`, `TSGetTime()`, `TSSetPostStep()`
3349: @*/
3350: PetscErrorCode TSPostStep(TS ts)
3351: {
3352:   PetscFunctionBegin;
3354:   if (ts->poststep) {
3355:     Vec              U;
3356:     PetscObjectId    idprev;
3357:     PetscBool        sameObject;
3358:     PetscObjectState sprev, spost;

3360:     PetscCall(TSGetSolution(ts, &U));
3361:     PetscCall(PetscObjectGetId((PetscObject)U, &idprev));
3362:     PetscCall(PetscObjectStateGet((PetscObject)U, &sprev));
3363:     PetscCallBack("TS callback poststep", (*ts->poststep)(ts));
3364:     PetscCall(TSGetSolution(ts, &U));
3365:     PetscCall(PetscObjectCompareId((PetscObject)U, idprev, &sameObject));
3366:     PetscCall(PetscObjectStateGet((PetscObject)U, &spost));
3367:     if (!sameObject || sprev != spost) PetscCall(TSRestartStep(ts));
3368:   }
3369:   PetscFunctionReturn(PETSC_SUCCESS);
3370: }

3372: /*@
3373:   TSInterpolate - Interpolate the solution computed during the previous step to an arbitrary location in the interval

3375:   Collective

3377:   Input Parameters:
3378: + ts - time stepping context
3379: - t  - time to interpolate to

3381:   Output Parameter:
3382: . U - state at given time

3384:   Level: intermediate

3386:   Developer Notes:
3387:   `TSInterpolate()` and the storing of previous steps/stages should be generalized to support delay differential equations and continuous adjoints.

3389: .seealso: [](ch_ts), `TS`, `TSSetExactFinalTime()`, `TSSolve()`
3390: @*/
3391: PetscErrorCode TSInterpolate(TS ts, PetscReal t, Vec U)
3392: {
3393:   PetscFunctionBegin;
3396:   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);
3397:   PetscUseTypeMethod(ts, interpolate, t, U);
3398:   PetscFunctionReturn(PETSC_SUCCESS);
3399: }

3401: /*@
3402:   TSStep - Steps one time step

3404:   Collective

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

3409:   Level: developer

3411:   Notes:
3412:   The public interface for the ODE/DAE solvers is `TSSolve()`, you should almost for sure be using that routine and not this routine.

3414:   The hook set using `TSSetPreStep()` is called before each attempt to take the step. In general, the time step size may
3415:   be changed due to adaptive error controller or solve failures. Note that steps may contain multiple stages.

3417:   This may over-step the final time provided in `TSSetMaxTime()` depending on the time-step used. `TSSolve()` interpolates to exactly the
3418:   time provided in `TSSetMaxTime()`. One can use `TSInterpolate()` to determine an interpolated solution within the final timestep.

3420: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSSetPostStage()`, `TSInterpolate()`
3421: @*/
3422: PetscErrorCode TSStep(TS ts)
3423: {
3424:   static PetscBool cite = PETSC_FALSE;
3425:   PetscReal        ptime;

3427:   PetscFunctionBegin;
3429:   PetscCall(PetscCitationsRegister("@article{tspaper,\n"
3430:                                    "  title         = {{PETSc/TS}: A Modern Scalable {DAE/ODE} Solver Library},\n"
3431:                                    "  author        = {Abhyankar, Shrirang and Brown, Jed and Constantinescu, Emil and Ghosh, Debojyoti and Smith, Barry F. and Zhang, Hong},\n"
3432:                                    "  journal       = {arXiv e-preprints},\n"
3433:                                    "  eprint        = {1806.01437},\n"
3434:                                    "  archivePrefix = {arXiv},\n"
3435:                                    "  year          = {2018}\n}\n",
3436:                                    &cite));
3437:   PetscCall(TSSetUp(ts));
3438:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));
3439:   if (ts->eval_times)
3440:     ts->eval_times->worktol = 0; /* In each step of TSSolve() 'eval_times->worktol' will be meaningfully defined (later) only once:
3441:                                                    in TSAdaptChoose() or TSEvent_dt_cap(), and then reused till the end of the step */

3443:   PetscCheck(ts->max_time < PETSC_MAX_REAL || ts->max_steps != PETSC_INT_MAX, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetMaxTime() or TSSetMaxSteps(), or use -ts_max_time <time> or -ts_max_steps <steps>");
3444:   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()");
3445:   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");

3447:   if (!ts->vec_sol0) PetscCall(VecDuplicate(ts->vec_sol, &ts->vec_sol0));
3448:   PetscCall(VecCopy(ts->vec_sol, ts->vec_sol0));
3449:   ts->time_step0 = ts->time_step;

3451:   if (!ts->steps) ts->ptime_prev = ts->ptime;
3452:   ptime = ts->ptime;

3454:   ts->ptime_prev_rollback = ts->ptime_prev;
3455:   ts->reason              = TS_CONVERGED_ITERATING;

3457:   PetscCall(PetscLogEventBegin(TS_Step, ts, 0, 0, 0));
3458:   PetscUseTypeMethod(ts, step);
3459:   PetscCall(PetscLogEventEnd(TS_Step, ts, 0, 0, 0));

3461:   if (ts->reason >= 0) {
3462:     ts->ptime_prev = ptime;
3463:     ts->steps++;
3464:     ts->steprollback = PETSC_FALSE;
3465:     ts->steprestart  = PETSC_FALSE;
3466:     ts->stepresize   = PETSC_FALSE;
3467:   }

3469:   if (ts->reason < 0 && ts->errorifstepfailed) {
3470:     PetscCall(TSMonitorCancel(ts));
3471:     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]);
3472:     SETERRQ(PetscObjectComm((PetscObject)ts), PETSC_ERR_NOT_CONVERGED, "TSStep has failed due to %s", TSConvergedReasons[ts->reason]);
3473:   }
3474:   PetscFunctionReturn(PETSC_SUCCESS);
3475: }

3477: /*@
3478:   TSEvaluateWLTE - Evaluate the weighted local truncation error norm
3479:   at the end of a time step with a given order of accuracy.

3481:   Collective

3483:   Input Parameters:
3484: + ts        - time stepping context
3485: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

3487:   Input/Output Parameter:
3488: . order - optional, desired order for the error evaluation or `PETSC_DECIDE`;
3489:            on output, the actual order of the error evaluation

3491:   Output Parameter:
3492: . wlte - the weighted local truncation error norm

3494:   Level: advanced

3496:   Note:
3497:   If the timestepper cannot evaluate the error in a particular step
3498:   (eg. in the first step or restart steps after event handling),
3499:   this routine returns wlte=-1.0 .

3501: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`, `TSErrorWeightedNorm()`
3502: @*/
3503: PetscErrorCode TSEvaluateWLTE(TS ts, NormType wnormtype, PetscInt *order, PetscReal *wlte)
3504: {
3505:   PetscFunctionBegin;
3509:   if (order) PetscAssertPointer(order, 3);
3511:   PetscAssertPointer(wlte, 4);
3512:   PetscCheck(wnormtype == NORM_2 || wnormtype == NORM_INFINITY, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No support for norm type %s", NormTypes[wnormtype]);
3513:   PetscUseTypeMethod(ts, evaluatewlte, wnormtype, order, wlte);
3514:   PetscFunctionReturn(PETSC_SUCCESS);
3515: }

3517: /*@
3518:   TSEvaluateStep - Evaluate the solution at the end of a time step with a given order of accuracy.

3520:   Collective

3522:   Input Parameters:
3523: + ts    - time stepping context
3524: . order - desired order of accuracy
3525: - done  - whether the step was evaluated at this order (pass `NULL` to generate an error if not available)

3527:   Output Parameter:
3528: . U - state at the end of the current step

3530:   Level: advanced

3532:   Notes:
3533:   This function cannot be called until all stages have been evaluated.

3535:   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.

3537: .seealso: [](ch_ts), `TS`, `TSStep()`, `TSAdapt`
3538: @*/
3539: PetscErrorCode TSEvaluateStep(TS ts, PetscInt order, Vec U, PetscBool *done)
3540: {
3541:   PetscFunctionBegin;
3545:   PetscUseTypeMethod(ts, evaluatestep, order, U, done);
3546:   PetscFunctionReturn(PETSC_SUCCESS);
3547: }

3549: /*@C
3550:   TSGetComputeInitialCondition - Get the function used to automatically compute an initial condition for the timestepping.

3552:   Not collective

3554:   Input Parameter:
3555: . ts - time stepping context

3557:   Output Parameter:
3558: . initCondition - The function which computes an initial condition

3560:   Calling sequence of `initCondition`:
3561: + ts - The timestepping context
3562: - u  - The input vector in which the initial condition is stored

3564:   Level: advanced

3566: .seealso: [](ch_ts), `TS`, `TSSetComputeInitialCondition()`, `TSComputeInitialCondition()`
3567: @*/
3568: PetscErrorCode TSGetComputeInitialCondition(TS ts, PetscErrorCode (**initCondition)(TS ts, Vec u))
3569: {
3570:   PetscFunctionBegin;
3572:   PetscAssertPointer(initCondition, 2);
3573:   *initCondition = ts->ops->initcondition;
3574:   PetscFunctionReturn(PETSC_SUCCESS);
3575: }

3577: /*@C
3578:   TSSetComputeInitialCondition - Set the function used to automatically compute an initial condition for the timestepping.

3580:   Logically collective

3582:   Input Parameters:
3583: + ts            - time stepping context
3584: - initCondition - The function which computes an initial condition

3586:   Calling sequence of `initCondition`:
3587: + ts - The timestepping context
3588: - e  - The input vector in which the initial condition is to be stored

3590:   Level: advanced

3592: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSComputeInitialCondition()`
3593: @*/
3594: PetscErrorCode TSSetComputeInitialCondition(TS ts, PetscErrorCode (*initCondition)(TS ts, Vec e))
3595: {
3596:   PetscFunctionBegin;
3599:   ts->ops->initcondition = initCondition;
3600:   PetscFunctionReturn(PETSC_SUCCESS);
3601: }

3603: /*@
3604:   TSComputeInitialCondition - Compute an initial condition for the timestepping using the function previously set with `TSSetComputeInitialCondition()`

3606:   Collective

3608:   Input Parameters:
3609: + ts - time stepping context
3610: - u  - The `Vec` to store the condition in which will be used in `TSSolve()`

3612:   Level: advanced

3614: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3615: @*/
3616: PetscErrorCode TSComputeInitialCondition(TS ts, Vec u)
3617: {
3618:   PetscFunctionBegin;
3621:   PetscTryTypeMethod(ts, initcondition, u);
3622:   PetscFunctionReturn(PETSC_SUCCESS);
3623: }

3625: /*@C
3626:   TSGetComputeExactError - Get the function used to automatically compute the exact error for the timestepping.

3628:   Not collective

3630:   Input Parameter:
3631: . ts - time stepping context

3633:   Output Parameter:
3634: . exactError - The function which computes the solution error

3636:   Calling sequence of `exactError`:
3637: + ts - The timestepping context
3638: . u  - The approximate solution vector
3639: - e  - The vector in which the error is stored

3641:   Level: advanced

3643: .seealso: [](ch_ts), `TS`, `TSComputeExactError()`
3644: @*/
3645: PetscErrorCode TSGetComputeExactError(TS ts, PetscErrorCode (**exactError)(TS ts, Vec u, Vec e))
3646: {
3647:   PetscFunctionBegin;
3649:   PetscAssertPointer(exactError, 2);
3650:   *exactError = ts->ops->exacterror;
3651:   PetscFunctionReturn(PETSC_SUCCESS);
3652: }

3654: /*@C
3655:   TSSetComputeExactError - Set the function used to automatically compute the exact error for the timestepping.

3657:   Logically collective

3659:   Input Parameters:
3660: + ts         - time stepping context
3661: - exactError - The function which computes the solution error

3663:   Calling sequence of `exactError`:
3664: + ts - The timestepping context
3665: . u  - The approximate solution vector
3666: - e  - The  vector in which the error is stored

3668:   Level: advanced

3670: .seealso: [](ch_ts), `TS`, `TSGetComputeExactError()`, `TSComputeExactError()`
3671: @*/
3672: PetscErrorCode TSSetComputeExactError(TS ts, PetscErrorCode (*exactError)(TS ts, Vec u, Vec e))
3673: {
3674:   PetscFunctionBegin;
3677:   ts->ops->exacterror = exactError;
3678:   PetscFunctionReturn(PETSC_SUCCESS);
3679: }

3681: /*@
3682:   TSComputeExactError - Compute the solution error for the timestepping using the function previously set with `TSSetComputeExactError()`

3684:   Collective

3686:   Input Parameters:
3687: + ts - time stepping context
3688: . u  - The approximate solution
3689: - e  - The `Vec` used to store the error

3691:   Level: advanced

3693: .seealso: [](ch_ts), `TS`, `TSGetComputeInitialCondition()`, `TSSetComputeInitialCondition()`, `TSSolve()`
3694: @*/
3695: PetscErrorCode TSComputeExactError(TS ts, Vec u, Vec e)
3696: {
3697:   PetscFunctionBegin;
3701:   PetscTryTypeMethod(ts, exacterror, u, e);
3702:   PetscFunctionReturn(PETSC_SUCCESS);
3703: }

3705: /*@C
3706:   TSSetResize - Sets the resize callbacks.

3708:   Logically Collective

3710:   Input Parameters:
3711: + ts       - The `TS` context obtained from `TSCreate()`
3712: . rollback - Whether a resize will restart the step
3713: . setup    - The setup function
3714: . transfer - The transfer function
3715: - ctx      - [optional] The user-defined context

3717:   Calling sequence of `setup`:
3718: + ts     - the `TS` context
3719: . step   - the current step
3720: . time   - the current time
3721: . state  - the current vector of state
3722: . resize - (output parameter) `PETSC_TRUE` if need resizing, `PETSC_FALSE` otherwise
3723: - ctx    - user defined context

3725:   Calling sequence of `transfer`:
3726: + ts      - the `TS` context
3727: . nv      - the number of vectors to be transferred
3728: . vecsin  - array of vectors to be transferred
3729: . vecsout - array of transferred vectors
3730: - ctx     - user defined context

3732:   Notes:
3733:   The `setup` function is called inside `TSSolve()` after `TSEventHandler()` or after `TSPostStep()`
3734:   depending on the `rollback` value: if `rollback` is true, then these callbacks behave as error indicators
3735:   and will flag the need to remesh and restart the current step. Otherwise, they will simply flag the solver
3736:   that the size of the discrete problem has changed.
3737:   In both cases, the solver will collect the needed vectors that will be
3738:   transferred from the old to the new sizes using the `transfer` callback. These vectors will include the
3739:   current solution vector, and other vectors needed by the specific solver used.
3740:   For example, `TSBDF` uses previous solutions vectors to solve for the next time step.
3741:   Other application specific objects associated with the solver, i.e. Jacobian matrices and `DM`,
3742:   will be automatically reset if the sizes are changed and they must be specified again by the user
3743:   inside the `transfer` function.
3744:   The input and output arrays passed to `transfer` are allocated by PETSc.
3745:   Vectors in `vecsout` must be created by the user.
3746:   Ownership of vectors in `vecsout` is transferred to PETSc.

3748:   Level: advanced

3750: .seealso: [](ch_ts), `TS`, `TSSetDM()`, `TSSetIJacobian()`, `TSSetRHSJacobian()`
3751: @*/
3752: 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)
3753: {
3754:   PetscFunctionBegin;
3756:   ts->resizerollback = rollback;
3757:   ts->resizesetup    = setup;
3758:   ts->resizetransfer = transfer;
3759:   ts->resizectx      = ctx;
3760:   PetscFunctionReturn(PETSC_SUCCESS);
3761: }

3763: /*
3764:   TSResizeRegisterOrRetrieve - Register or import vectors transferred with `TSResize()`.

3766:   Collective

3768:   Input Parameters:
3769: + ts   - The `TS` context obtained from `TSCreate()`
3770: - 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.

3772:   Level: developer

3774:   Note:
3775:   `TSResizeRegisterOrRetrieve()` is declared PETSC_INTERN since it is
3776:    used within time stepping implementations,
3777:    so most users would not generally call this routine themselves.

3779: .seealso: [](ch_ts), `TS`, `TSSetResize()`
3780: @*/
3781: static PetscErrorCode TSResizeRegisterOrRetrieve(TS ts, PetscBool flg)
3782: {
3783:   PetscFunctionBegin;
3785:   PetscTryTypeMethod(ts, resizeregister, flg);
3786:   /* PetscTryTypeMethod(adapt, resizeregister, flg); */
3787:   PetscFunctionReturn(PETSC_SUCCESS);
3788: }

3790: static PetscErrorCode TSResizeReset(TS ts)
3791: {
3792:   PetscFunctionBegin;
3794:   PetscCall(PetscObjectListDestroy(&ts->resizetransferobjs));
3795:   PetscFunctionReturn(PETSC_SUCCESS);
3796: }

3798: static PetscErrorCode TSResizeTransferVecs(TS ts, PetscInt cnt, Vec vecsin[], Vec vecsout[])
3799: {
3800:   PetscFunctionBegin;
3803:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPush(vecsin[i]));
3804:   if (ts->resizetransfer) {
3805:     PetscCall(PetscInfo(ts, "Transferring %" PetscInt_FMT " vectors\n", cnt));
3806:     PetscCallBack("TS callback resize transfer", (*ts->resizetransfer)(ts, cnt, vecsin, vecsout, ts->resizectx));
3807:   }
3808:   for (PetscInt i = 0; i < cnt; i++) PetscCall(VecLockReadPop(vecsin[i]));
3809:   PetscFunctionReturn(PETSC_SUCCESS);
3810: }

3812: /*@C
3813:   TSResizeRegisterVec - Register a vector to be transferred with `TSResize()`.

3815:   Collective

3817:   Input Parameters:
3818: + ts   - The `TS` context obtained from `TSCreate()`
3819: . name - A string identifying the vector
3820: - vec  - The vector

3822:   Level: developer

3824:   Note:
3825:   `TSResizeRegisterVec()` is typically used within time stepping implementations,
3826:   so most users would not generally call this routine themselves.

3828: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRetrieveVec()`
3829: @*/
3830: PetscErrorCode TSResizeRegisterVec(TS ts, const char name[], Vec vec)
3831: {
3832:   PetscFunctionBegin;
3834:   PetscAssertPointer(name, 2);
3836:   PetscCall(PetscObjectListAdd(&ts->resizetransferobjs, name, (PetscObject)vec));
3837:   PetscFunctionReturn(PETSC_SUCCESS);
3838: }

3840: /*@C
3841:   TSResizeRetrieveVec - Retrieve a vector registered with `TSResizeRegisterVec()`.

3843:   Collective

3845:   Input Parameters:
3846: + ts   - The `TS` context obtained from `TSCreate()`
3847: . name - A string identifying the vector
3848: - vec  - The vector

3850:   Level: developer

3852:   Note:
3853:   `TSResizeRetrieveVec()` is typically used within time stepping implementations,
3854:   so most users would not generally call this routine themselves.

3856: .seealso: [](ch_ts), `TS`, `TSSetResize()`, `TSResize()`, `TSResizeRegisterVec()`
3857: @*/
3858: PetscErrorCode TSResizeRetrieveVec(TS ts, const char name[], Vec *vec)
3859: {
3860:   PetscFunctionBegin;
3862:   PetscAssertPointer(name, 2);
3863:   PetscAssertPointer(vec, 3);
3864:   PetscCall(PetscObjectListFind(ts->resizetransferobjs, name, (PetscObject *)vec));
3865:   PetscFunctionReturn(PETSC_SUCCESS);
3866: }

3868: static PetscErrorCode TSResizeGetVecArray(TS ts, PetscInt *nv, const char **names[], Vec *vecs[])
3869: {
3870:   PetscInt        cnt;
3871:   PetscObjectList tmp;
3872:   Vec            *vecsin  = NULL;
3873:   const char    **namesin = NULL;

3875:   PetscFunctionBegin;
3876:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next)
3877:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) cnt++;
3878:   if (names) PetscCall(PetscMalloc1(cnt, &namesin));
3879:   if (vecs) PetscCall(PetscMalloc1(cnt, &vecsin));
3880:   for (tmp = ts->resizetransferobjs, cnt = 0; tmp; tmp = tmp->next) {
3881:     if (tmp->obj && tmp->obj->classid == VEC_CLASSID) {
3882:       if (vecs) vecsin[cnt] = (Vec)tmp->obj;
3883:       if (names) namesin[cnt] = tmp->name;
3884:       cnt++;
3885:     }
3886:   }
3887:   if (nv) *nv = cnt;
3888:   if (names) *names = namesin;
3889:   if (vecs) *vecs = vecsin;
3890:   PetscFunctionReturn(PETSC_SUCCESS);
3891: }

3893: /*@
3894:   TSResize - Runs the user-defined transfer functions provided with `TSSetResize()`

3896:   Collective

3898:   Input Parameter:
3899: . ts - The `TS` context obtained from `TSCreate()`

3901:   Level: developer

3903:   Note:
3904:   `TSResize()` is typically used within time stepping implementations,
3905:   so most users would not generally call this routine themselves.

3907: .seealso: [](ch_ts), `TS`, `TSSetResize()`
3908: @*/
3909: PetscErrorCode TSResize(TS ts)
3910: {
3911:   PetscInt     nv      = 0;
3912:   const char **names   = NULL;
3913:   Vec         *vecsin  = NULL;
3914:   const char  *solname = "ts:vec_sol";

3916:   PetscFunctionBegin;
3918:   if (!ts->resizesetup) PetscFunctionReturn(PETSC_SUCCESS);
3919:   if (ts->resizesetup) {
3920:     PetscCall(VecLockReadPush(ts->vec_sol));
3921:     PetscCallBack("TS callback resize setup", (*ts->resizesetup)(ts, ts->steps, ts->ptime, ts->vec_sol, &ts->stepresize, ts->resizectx));
3922:     PetscCall(VecLockReadPop(ts->vec_sol));
3923:     if (ts->stepresize) {
3924:       if (ts->resizerollback) {
3925:         PetscCall(TSRollBack(ts));
3926:         ts->time_step = ts->time_step0;
3927:       }
3928:       PetscCall(TSResizeRegisterVec(ts, solname, ts->vec_sol));
3929:       PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_TRUE)); /* specific impls register their own objects */
3930:     }
3931:   }

3933:   PetscCall(TSResizeGetVecArray(ts, &nv, &names, &vecsin));
3934:   if (nv) {
3935:     Vec *vecsout, vecsol;

3937:     /* Reset internal objects */
3938:     PetscCall(TSReset(ts));

3940:     /* Transfer needed vectors (users can call SetJacobian, SetDM, etc. here) */
3941:     PetscCall(PetscCalloc1(nv, &vecsout));
3942:     PetscCall(TSResizeTransferVecs(ts, nv, vecsin, vecsout));
3943:     for (PetscInt i = 0; i < nv; i++) {
3944:       const char *name;
3945:       char       *oname;

3947:       PetscCall(PetscObjectGetName((PetscObject)vecsin[i], &name));
3948:       PetscCall(PetscStrallocpy(name, &oname));
3949:       PetscCall(TSResizeRegisterVec(ts, names[i], vecsout[i]));
3950:       if (vecsout[i]) PetscCall(PetscObjectSetName((PetscObject)vecsout[i], oname));
3951:       PetscCall(PetscFree(oname));
3952:       PetscCall(VecDestroy(&vecsout[i]));
3953:     }
3954:     PetscCall(PetscFree(vecsout));
3955:     PetscCall(TSResizeRegisterOrRetrieve(ts, PETSC_FALSE)); /* specific impls import the transferred objects */

3957:     PetscCall(TSResizeRetrieveVec(ts, solname, &vecsol));
3958:     if (vecsol) PetscCall(TSSetSolution(ts, vecsol));
3959:     PetscAssert(ts->vec_sol, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_NULL, "Missing TS solution");
3960:   }

3962:   PetscCall(PetscFree(names));
3963:   PetscCall(PetscFree(vecsin));
3964:   PetscCall(TSResizeReset(ts));
3965:   PetscFunctionReturn(PETSC_SUCCESS);
3966: }

3968: /*@
3969:   TSSolve - Steps the requested number of timesteps.

3971:   Collective

3973:   Input Parameters:
3974: + ts - the `TS` context obtained from `TSCreate()`
3975: - u  - the solution vector  (can be null if `TSSetSolution()` was used and `TSSetExactFinalTime`(ts,`TS_EXACTFINALTIME_MATCHSTEP`) was not used,
3976:        otherwise it must contain the initial conditions and will contain the solution at the final requested time

3978:   Level: beginner

3980:   Notes:
3981:   The final time returned by this function may be different from the time of the internally
3982:   held state accessible by `TSGetSolution()` and `TSGetTime()` because the method may have
3983:   stepped over the final time.

3985: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetSolution()`, `TSStep()`, `TSGetTime()`, `TSGetSolveTime()`
3986: @*/
3987: PetscErrorCode TSSolve(TS ts, Vec u)
3988: {
3989:   Vec solution;

3991:   PetscFunctionBegin;

3995:   PetscCall(TSSetExactFinalTimeDefault(ts));
3996:   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 */
3997:     if (!ts->vec_sol || u == ts->vec_sol) {
3998:       PetscCall(VecDuplicate(u, &solution));
3999:       PetscCall(TSSetSolution(ts, solution));
4000:       PetscCall(VecDestroy(&solution)); /* grant ownership */
4001:     }
4002:     PetscCall(VecCopy(u, ts->vec_sol));
4003:     PetscCheck(!ts->forward_solve, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "Sensitivity analysis does not support the mode TS_EXACTFINALTIME_INTERPOLATE");
4004:   } else if (u) PetscCall(TSSetSolution(ts, u));
4005:   PetscCall(TSSetUp(ts));
4006:   PetscCall(TSTrajectorySetUp(ts->trajectory, ts));

4008:   PetscCheck(ts->max_time < PETSC_MAX_REAL || ts->max_steps != PETSC_INT_MAX, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "You must call TSSetMaxTime() or TSSetMaxSteps(), or use -ts_max_time <time> or -ts_max_steps <steps>");
4009:   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()");
4010:   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");
4011:   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");

4013:   if (ts->eval_times) {
4014:     for (PetscInt i = 0; i < ts->eval_times->num_time_points; i++) {
4015:       PetscBool is_close = PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[i], ts->eval_times->reltol * ts->time_step + ts->eval_times->abstol, 0);
4016:       if (ts->ptime <= ts->eval_times->time_points[i] || is_close) {
4017:         ts->eval_times->time_point_idx = i;
4018:         if (is_close) { /* starting point in evaluation times */
4019:           PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_ctr]));
4020:           ts->eval_times->sol_times[ts->eval_times->sol_ctr] = ts->ptime;
4021:           ts->eval_times->sol_ctr++;
4022:           ts->eval_times->time_point_idx++;
4023:         }
4024:         break;
4025:       }
4026:     }
4027:   }

4029:   if (ts->forward_solve) PetscCall(TSForwardSetUp(ts));

4031:   /* reset number of steps only when the step is not restarted. ARKIMEX
4032:      restarts the step after an event. Resetting these counters in such case causes
4033:      TSTrajectory to incorrectly save the output files
4034:   */
4035:   /* reset time step and iteration counters */
4036:   if (!ts->steps) {
4037:     ts->ksp_its           = 0;
4038:     ts->snes_its          = 0;
4039:     ts->num_snes_failures = 0;
4040:     ts->reject            = 0;
4041:     ts->steprestart       = PETSC_TRUE;
4042:     ts->steprollback      = PETSC_FALSE;
4043:     ts->stepresize        = PETSC_FALSE;
4044:     ts->rhsjacobian.time  = PETSC_MIN_REAL;
4045:   }

4047:   /* make sure initial time step does not overshoot final time or the next point in evaluation times */
4048:   if (ts->exact_final_time == TS_EXACTFINALTIME_MATCHSTEP) {
4049:     PetscReal maxdt;
4050:     PetscReal dt = ts->time_step;

4052:     if (ts->eval_times) maxdt = ts->eval_times->time_points[ts->eval_times->time_point_idx] - ts->ptime;
4053:     else maxdt = ts->max_time - ts->ptime;
4054:     ts->time_step = dt >= maxdt ? maxdt : (PetscIsCloseAtTol(dt, maxdt, 10 * PETSC_MACHINE_EPSILON, 0) ? maxdt : dt);
4055:   }
4056:   ts->reason = TS_CONVERGED_ITERATING;

4058:   {
4059:     PetscViewer       viewer;
4060:     PetscViewerFormat format;
4061:     PetscBool         flg;
4062:     static PetscBool  incall = PETSC_FALSE;

4064:     if (!incall) {
4065:       /* Estimate the convergence rate of the time discretization */
4066:       PetscCall(PetscOptionsCreateViewer(PetscObjectComm((PetscObject)ts), ((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_estimate", &viewer, &format, &flg));
4067:       if (flg) {
4068:         PetscConvEst conv;
4069:         DM           dm;
4070:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4071:         PetscInt     Nf;
4072:         PetscBool    checkTemporal = PETSC_TRUE;

4074:         incall = PETSC_TRUE;
4075:         PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_convergence_temporal", &checkTemporal, &flg));
4076:         PetscCall(TSGetDM(ts, &dm));
4077:         PetscCall(DMGetNumFields(dm, &Nf));
4078:         PetscCall(PetscCalloc1(PetscMax(Nf, 1), &alpha));
4079:         PetscCall(PetscConvEstCreate(PetscObjectComm((PetscObject)ts), &conv));
4080:         PetscCall(PetscConvEstUseTS(conv, checkTemporal));
4081:         PetscCall(PetscConvEstSetSolver(conv, (PetscObject)ts));
4082:         PetscCall(PetscConvEstSetFromOptions(conv));
4083:         PetscCall(PetscConvEstSetUp(conv));
4084:         PetscCall(PetscConvEstGetConvRate(conv, alpha));
4085:         PetscCall(PetscViewerPushFormat(viewer, format));
4086:         PetscCall(PetscConvEstRateView(conv, alpha, viewer));
4087:         PetscCall(PetscViewerPopFormat(viewer));
4088:         PetscCall(PetscViewerDestroy(&viewer));
4089:         PetscCall(PetscConvEstDestroy(&conv));
4090:         PetscCall(PetscFree(alpha));
4091:         incall = PETSC_FALSE;
4092:       }
4093:     }
4094:   }

4096:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view_pre"));

4098:   if (ts->ops->solve) { /* This private interface is transitional and should be removed when all implementations are updated. */
4099:     PetscUseTypeMethod(ts, solve);
4100:     if (u) PetscCall(VecCopy(ts->vec_sol, u));
4101:     ts->solvetime = ts->ptime;
4102:     solution      = ts->vec_sol;
4103:   } else { /* Step the requested number of timesteps. */
4104:     if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4105:     else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;

4107:     if (!ts->steps) {
4108:       PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4109:       PetscCall(TSEventInitialize(ts->event, ts, ts->ptime, ts->vec_sol));
4110:     }

4112:     while (!ts->reason) {
4113:       PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));
4114:       if (!ts->steprollback || (ts->stepresize && ts->resizerollback)) PetscCall(TSPreStep(ts));
4115:       PetscCall(TSStep(ts));
4116:       if (ts->testjacobian) PetscCall(TSRHSJacobianTest(ts, NULL));
4117:       if (ts->testjacobiantranspose) PetscCall(TSRHSJacobianTestTranspose(ts, NULL));
4118:       if (ts->quadraturets && ts->costintegralfwd) { /* Must evaluate the cost integral before event is handled. The cost integral value can also be rolled back. */
4119:         if (ts->reason >= 0) ts->steps--;            /* Revert the step number changed by TSStep() */
4120:         PetscCall(TSForwardCostIntegral(ts));
4121:         if (ts->reason >= 0) ts->steps++;
4122:       }
4123:       if (ts->forward_solve) {            /* compute forward sensitivities before event handling because postevent() may change RHS and jump conditions may have to be applied */
4124:         if (ts->reason >= 0) ts->steps--; /* Revert the step number changed by TSStep() */
4125:         PetscCall(TSForwardStep(ts));
4126:         if (ts->reason >= 0) ts->steps++;
4127:       }
4128:       PetscCall(TSPostEvaluate(ts));
4129:       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. */
4130:       if (ts->steprollback) PetscCall(TSPostEvaluate(ts));
4131:       if (!ts->steprollback && ts->resizerollback) PetscCall(TSResize(ts));
4132:       /* check convergence */
4133:       if (!ts->reason) {
4134:         if (ts->steps >= ts->max_steps) ts->reason = TS_CONVERGED_ITS;
4135:         else if (ts->ptime >= ts->max_time) ts->reason = TS_CONVERGED_TIME;
4136:       }
4137:       if (!ts->steprollback) {
4138:         PetscCall(TSTrajectorySet(ts->trajectory, ts, ts->steps, ts->ptime, ts->vec_sol));
4139:         PetscCall(TSPostStep(ts));
4140:         if (!ts->resizerollback) PetscCall(TSResize(ts));

4142:         if (ts->eval_times && ts->eval_times->time_point_idx < ts->eval_times->num_time_points && ts->reason >= 0) {
4143:           PetscCheck(ts->eval_times->worktol > 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_PLIB, "Unexpected state !(eval_times->worktol > 0) in TSSolve()");
4144:           if (PetscIsCloseAtTol(ts->ptime, ts->eval_times->time_points[ts->eval_times->time_point_idx], ts->eval_times->worktol, 0)) {
4145:             ts->eval_times->sol_times[ts->eval_times->sol_ctr] = ts->ptime;
4146:             PetscCall(VecCopy(ts->vec_sol, ts->eval_times->sol_vecs[ts->eval_times->sol_ctr]));
4147:             ts->eval_times->sol_ctr++;
4148:             ts->eval_times->time_point_idx++;
4149:           }
4150:         }
4151:       }
4152:     }
4153:     PetscCall(TSMonitor(ts, ts->steps, ts->ptime, ts->vec_sol));

4155:     if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE && ts->ptime > ts->max_time) {
4156:       if (!u) u = ts->vec_sol;
4157:       PetscCall(TSInterpolate(ts, ts->max_time, u));
4158:       ts->solvetime = ts->max_time;
4159:       solution      = u;
4160:       PetscCall(TSMonitor(ts, -1, ts->solvetime, solution));
4161:     } else {
4162:       if (u) PetscCall(VecCopy(ts->vec_sol, u));
4163:       ts->solvetime = ts->ptime;
4164:       solution      = ts->vec_sol;
4165:     }
4166:   }

4168:   PetscCall(TSViewFromOptions(ts, NULL, "-ts_view"));
4169:   PetscCall(VecViewFromOptions(solution, (PetscObject)ts, "-ts_view_solution"));
4170:   PetscCall(PetscObjectSAWsBlock((PetscObject)ts));
4171:   if (ts->adjoint_solve) PetscCall(TSAdjointSolve(ts));
4172:   PetscFunctionReturn(PETSC_SUCCESS);
4173: }

4175: /*@
4176:   TSGetTime - Gets the time of the most recently completed step.

4178:   Not Collective

4180:   Input Parameter:
4181: . ts - the `TS` context obtained from `TSCreate()`

4183:   Output Parameter:
4184: . t - the current time. This time may not corresponds to the final time set with `TSSetMaxTime()`, use `TSGetSolveTime()`.

4186:   Level: beginner

4188:   Note:
4189:   When called during time step evaluation (e.g. during residual evaluation or via hooks set using `TSSetPreStep()`,
4190:   `TSSetPreStage()`, `TSSetPostStage()`, or `TSSetPostStep()`), the time is the time at the start of the step being evaluated.

4192: .seealso: [](ch_ts), `TS`, `TSGetSolveTime()`, `TSSetTime()`, `TSGetTimeStep()`, `TSGetStepNumber()`
4193: @*/
4194: PetscErrorCode TSGetTime(TS ts, PetscReal *t)
4195: {
4196:   PetscFunctionBegin;
4198:   PetscAssertPointer(t, 2);
4199:   *t = ts->ptime;
4200:   PetscFunctionReturn(PETSC_SUCCESS);
4201: }

4203: /*@
4204:   TSGetPrevTime - Gets the starting time of the previously completed step.

4206:   Not Collective

4208:   Input Parameter:
4209: . ts - the `TS` context obtained from `TSCreate()`

4211:   Output Parameter:
4212: . t - the previous time

4214:   Level: beginner

4216: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSGetSolveTime()`, `TSGetTimeStep()`
4217: @*/
4218: PetscErrorCode TSGetPrevTime(TS ts, PetscReal *t)
4219: {
4220:   PetscFunctionBegin;
4222:   PetscAssertPointer(t, 2);
4223:   *t = ts->ptime_prev;
4224:   PetscFunctionReturn(PETSC_SUCCESS);
4225: }

4227: /*@
4228:   TSSetTime - Allows one to reset the time.

4230:   Logically Collective

4232:   Input Parameters:
4233: + ts - the `TS` context obtained from `TSCreate()`
4234: - t  - the time

4236:   Level: intermediate

4238: .seealso: [](ch_ts), `TS`, `TSGetTime()`, `TSSetMaxSteps()`
4239: @*/
4240: PetscErrorCode TSSetTime(TS ts, PetscReal t)
4241: {
4242:   PetscFunctionBegin;
4245:   ts->ptime = t;
4246:   PetscFunctionReturn(PETSC_SUCCESS);
4247: }

4249: /*@
4250:   TSSetOptionsPrefix - Sets the prefix used for searching for all
4251:   TS options in the database.

4253:   Logically Collective

4255:   Input Parameters:
4256: + ts     - The `TS` context
4257: - prefix - The prefix to prepend to all option names

4259:   Level: advanced

4261:   Note:
4262:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4263:   The first character of all runtime options is AUTOMATICALLY the
4264:   hyphen.

4266: .seealso: [](ch_ts), `TS`, `TSSetFromOptions()`, `TSAppendOptionsPrefix()`
4267: @*/
4268: PetscErrorCode TSSetOptionsPrefix(TS ts, const char prefix[])
4269: {
4270:   SNES snes;

4272:   PetscFunctionBegin;
4274:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)ts, prefix));
4275:   PetscCall(TSGetSNES(ts, &snes));
4276:   PetscCall(SNESSetOptionsPrefix(snes, prefix));
4277:   PetscFunctionReturn(PETSC_SUCCESS);
4278: }

4280: /*@
4281:   TSAppendOptionsPrefix - Appends to the prefix used for searching for all
4282:   TS options in the database.

4284:   Logically Collective

4286:   Input Parameters:
4287: + ts     - The `TS` context
4288: - prefix - The prefix to prepend to all option names

4290:   Level: advanced

4292:   Note:
4293:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4294:   The first character of all runtime options is AUTOMATICALLY the
4295:   hyphen.

4297: .seealso: [](ch_ts), `TS`, `TSGetOptionsPrefix()`, `TSSetOptionsPrefix()`, `TSSetFromOptions()`
4298: @*/
4299: PetscErrorCode TSAppendOptionsPrefix(TS ts, const char prefix[])
4300: {
4301:   SNES snes;

4303:   PetscFunctionBegin;
4305:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)ts, prefix));
4306:   PetscCall(TSGetSNES(ts, &snes));
4307:   PetscCall(SNESAppendOptionsPrefix(snes, prefix));
4308:   PetscFunctionReturn(PETSC_SUCCESS);
4309: }

4311: /*@
4312:   TSGetOptionsPrefix - Sets the prefix used for searching for all
4313:   `TS` options in the database.

4315:   Not Collective

4317:   Input Parameter:
4318: . ts - The `TS` context

4320:   Output Parameter:
4321: . prefix - A pointer to the prefix string used

4323:   Level: intermediate

4325: .seealso: [](ch_ts), `TS`, `TSAppendOptionsPrefix()`, `TSSetFromOptions()`
4326: @*/
4327: PetscErrorCode TSGetOptionsPrefix(TS ts, const char *prefix[])
4328: {
4329:   PetscFunctionBegin;
4331:   PetscAssertPointer(prefix, 2);
4332:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)ts, prefix));
4333:   PetscFunctionReturn(PETSC_SUCCESS);
4334: }

4336: /*@C
4337:   TSGetRHSJacobian - Returns the Jacobian J at the present timestep.

4339:   Not Collective, but parallel objects are returned if ts is parallel

4341:   Input Parameter:
4342: . ts - The `TS` context obtained from `TSCreate()`

4344:   Output Parameters:
4345: + Amat - The (approximate) Jacobian J of G, where U_t = G(U,t)  (or `NULL`)
4346: . Pmat - The matrix from which the preconditioner is constructed, usually the same as `Amat`  (or `NULL`)
4347: . func - Function to compute the Jacobian of the RHS  (or `NULL`)
4348: - ctx  - User-defined context for Jacobian evaluation routine  (or `NULL`)

4350:   Level: intermediate

4352:   Note:
4353:   You can pass in `NULL` for any return argument you do not need.

4355: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`

4357: @*/
4358: PetscErrorCode TSGetRHSJacobian(TS ts, Mat *Amat, Mat *Pmat, TSRHSJacobianFn **func, void **ctx)
4359: {
4360:   DM dm;

4362:   PetscFunctionBegin;
4363:   if (Amat || Pmat) {
4364:     SNES snes;
4365:     PetscCall(TSGetSNES(ts, &snes));
4366:     PetscCall(SNESSetUpMatrices(snes));
4367:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4368:   }
4369:   PetscCall(TSGetDM(ts, &dm));
4370:   PetscCall(DMTSGetRHSJacobian(dm, func, ctx));
4371:   PetscFunctionReturn(PETSC_SUCCESS);
4372: }

4374: /*@C
4375:   TSGetIJacobian - Returns the implicit Jacobian at the present timestep.

4377:   Not Collective, but parallel objects are returned if ts is parallel

4379:   Input Parameter:
4380: . ts - The `TS` context obtained from `TSCreate()`

4382:   Output Parameters:
4383: + Amat - The (approximate) Jacobian of F(t,U,U_t)
4384: . Pmat - The matrix from which the preconditioner is constructed, often the same as `Amat`
4385: . f    - The function to compute the matrices
4386: - ctx  - User-defined context for Jacobian evaluation routine

4388:   Level: advanced

4390:   Note:
4391:   You can pass in `NULL` for any return argument you do not need.

4393: .seealso: [](ch_ts), `TS`, `TSGetTimeStep()`, `TSGetRHSJacobian()`, `TSGetMatrices()`, `TSGetTime()`, `TSGetStepNumber()`
4394: @*/
4395: PetscErrorCode TSGetIJacobian(TS ts, Mat *Amat, Mat *Pmat, TSIJacobianFn **f, void **ctx)
4396: {
4397:   DM dm;

4399:   PetscFunctionBegin;
4400:   if (Amat || Pmat) {
4401:     SNES snes;
4402:     PetscCall(TSGetSNES(ts, &snes));
4403:     PetscCall(SNESSetUpMatrices(snes));
4404:     PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
4405:   }
4406:   PetscCall(TSGetDM(ts, &dm));
4407:   PetscCall(DMTSGetIJacobian(dm, f, ctx));
4408:   PetscFunctionReturn(PETSC_SUCCESS);
4409: }

4411: #include <petsc/private/dmimpl.h>
4412: /*@
4413:   TSSetDM - Sets the `DM` that may be used by some nonlinear solvers or preconditioners under the `TS`

4415:   Logically Collective

4417:   Input Parameters:
4418: + ts - the `TS` integrator object
4419: - dm - the dm, cannot be `NULL`

4421:   Level: intermediate

4423:   Notes:
4424:   A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
4425:   even when not using interfaces like `DMTSSetIFunction()`.  Use `DMClone()` to get a distinct `DM` when solving
4426:   different problems using the same function space.

4428: .seealso: [](ch_ts), `TS`, `DM`, `TSGetDM()`, `SNESSetDM()`, `SNESGetDM()`
4429: @*/
4430: PetscErrorCode TSSetDM(TS ts, DM dm)
4431: {
4432:   SNES snes;
4433:   DMTS tsdm;

4435:   PetscFunctionBegin;
4438:   PetscCall(PetscObjectReference((PetscObject)dm));
4439:   if (ts->dm) { /* Move the DMTS context over to the new DM unless the new DM already has one */
4440:     if (ts->dm->dmts && !dm->dmts) {
4441:       PetscCall(DMCopyDMTS(ts->dm, dm));
4442:       PetscCall(DMGetDMTS(ts->dm, &tsdm));
4443:       /* Grant write privileges to the replacement DM */
4444:       if (tsdm->originaldm == ts->dm) tsdm->originaldm = dm;
4445:     }
4446:     PetscCall(DMDestroy(&ts->dm));
4447:   }
4448:   ts->dm = dm;

4450:   PetscCall(TSGetSNES(ts, &snes));
4451:   PetscCall(SNESSetDM(snes, dm));
4452:   PetscFunctionReturn(PETSC_SUCCESS);
4453: }

4455: /*@
4456:   TSGetDM - Gets the `DM` that may be used by some preconditioners

4458:   Not Collective

4460:   Input Parameter:
4461: . ts - the `TS`

4463:   Output Parameter:
4464: . dm - the `DM`

4466:   Level: intermediate

4468: .seealso: [](ch_ts), `TS`, `DM`, `TSSetDM()`, `SNESSetDM()`, `SNESGetDM()`
4469: @*/
4470: PetscErrorCode TSGetDM(TS ts, DM *dm)
4471: {
4472:   PetscFunctionBegin;
4474:   if (!ts->dm) {
4475:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)ts), &ts->dm));
4476:     if (ts->snes) PetscCall(SNESSetDM(ts->snes, ts->dm));
4477:   }
4478:   *dm = ts->dm;
4479:   PetscFunctionReturn(PETSC_SUCCESS);
4480: }

4482: /*@
4483:   SNESTSFormFunction - Function to evaluate nonlinear residual

4485:   Logically Collective

4487:   Input Parameters:
4488: + snes - nonlinear solver
4489: . U    - the current state at which to evaluate the residual
4490: - ctx  - user context, must be a TS

4492:   Output Parameter:
4493: . F - the nonlinear residual

4495:   Level: advanced

4497:   Note:
4498:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.
4499:   It is most frequently passed to `MatFDColoringSetFunction()`.

4501: .seealso: [](ch_ts), `SNESSetFunction()`, `MatFDColoringSetFunction()`
4502: @*/
4503: PetscErrorCode SNESTSFormFunction(SNES snes, Vec U, Vec F, void *ctx)
4504: {
4505:   TS ts = (TS)ctx;

4507:   PetscFunctionBegin;
4512:   PetscCheck(ts->ops->snesfunction, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesfunction for TS of type %s", ((PetscObject)ts)->type_name);
4513:   PetscCall((*ts->ops->snesfunction)(snes, U, F, ts));
4514:   PetscFunctionReturn(PETSC_SUCCESS);
4515: }

4517: /*@
4518:   SNESTSFormJacobian - Function to evaluate the Jacobian

4520:   Collective

4522:   Input Parameters:
4523: + snes - nonlinear solver
4524: . U    - the current state at which to evaluate the residual
4525: - ctx  - user context, must be a `TS`

4527:   Output Parameters:
4528: + A - the Jacobian
4529: - B - the matrix used to construct the preconditioner (often the same as `A`)

4531:   Level: developer

4533:   Note:
4534:   This function is not normally called by users and is automatically registered with the `SNES` used by `TS`.

4536: .seealso: [](ch_ts), `SNESSetJacobian()`
4537: @*/
4538: PetscErrorCode SNESTSFormJacobian(SNES snes, Vec U, Mat A, Mat B, void *ctx)
4539: {
4540:   TS ts = (TS)ctx;

4542:   PetscFunctionBegin;
4548:   PetscCheck(ts->ops->snesjacobian, PetscObjectComm((PetscObject)ts), PETSC_ERR_SUP, "No method snesjacobian for TS of type %s", ((PetscObject)ts)->type_name);
4549:   PetscCall((*ts->ops->snesjacobian)(snes, U, A, B, ts));
4550:   PetscFunctionReturn(PETSC_SUCCESS);
4551: }

4553: /*@C
4554:   TSComputeRHSFunctionLinear - Evaluate the right-hand side via the user-provided Jacobian, for linear problems Udot = A U only

4556:   Collective

4558:   Input Parameters:
4559: + ts  - time stepping context
4560: . t   - time at which to evaluate
4561: . U   - state at which to evaluate
4562: - ctx - context

4564:   Output Parameter:
4565: . F - right-hand side

4567:   Level: intermediate

4569:   Note:
4570:   This function is intended to be passed to `TSSetRHSFunction()` to evaluate the right-hand side for linear problems.
4571:   The matrix (and optionally the evaluation context) should be passed to `TSSetRHSJacobian()`.

4573: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSJacobianConstant()`
4574: @*/
4575: PetscErrorCode TSComputeRHSFunctionLinear(TS ts, PetscReal t, Vec U, Vec F, void *ctx)
4576: {
4577:   Mat Arhs, Brhs;

4579:   PetscFunctionBegin;
4580:   PetscCall(TSGetRHSMats_Private(ts, &Arhs, &Brhs));
4581:   /* undo the damage caused by shifting */
4582:   PetscCall(TSRecoverRHSJacobian(ts, Arhs, Brhs));
4583:   PetscCall(TSComputeRHSJacobian(ts, t, U, Arhs, Brhs));
4584:   PetscCall(MatMult(Arhs, U, F));
4585:   PetscFunctionReturn(PETSC_SUCCESS);
4586: }

4588: /*@C
4589:   TSComputeRHSJacobianConstant - Reuses a Jacobian that is time-independent.

4591:   Collective

4593:   Input Parameters:
4594: + ts  - time stepping context
4595: . t   - time at which to evaluate
4596: . U   - state at which to evaluate
4597: - ctx - context

4599:   Output Parameters:
4600: + A - Jacobian
4601: - B - matrix used to construct the preconditioner, often the same as `A`

4603:   Level: intermediate

4605:   Note:
4606:   This function is intended to be passed to `TSSetRHSJacobian()` to evaluate the Jacobian for linear time-independent problems.

4608: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSSetRHSJacobian()`, `TSComputeRHSFunctionLinear()`
4609: @*/
4610: PetscErrorCode TSComputeRHSJacobianConstant(TS ts, PetscReal t, Vec U, Mat A, Mat B, void *ctx)
4611: {
4612:   PetscFunctionBegin;
4613:   PetscFunctionReturn(PETSC_SUCCESS);
4614: }

4616: /*@C
4617:   TSComputeIFunctionLinear - Evaluate the left hand side via the user-provided Jacobian, for linear problems only

4619:   Collective

4621:   Input Parameters:
4622: + ts   - time stepping context
4623: . t    - time at which to evaluate
4624: . U    - state at which to evaluate
4625: . Udot - time derivative of state vector
4626: - ctx  - context

4628:   Output Parameter:
4629: . F - left hand side

4631:   Level: intermediate

4633:   Notes:
4634:   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
4635:   user is required to write their own `TSComputeIFunction()`.
4636:   This function is intended to be passed to `TSSetIFunction()` to evaluate the left hand side for linear problems.
4637:   The matrix (and optionally the evaluation context) should be passed to `TSSetIJacobian()`.

4639:   Note that using this function is NOT equivalent to using `TSComputeRHSFunctionLinear()` since that solves Udot = A U

4641: .seealso: [](ch_ts), `TS`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIJacobianConstant()`, `TSComputeRHSFunctionLinear()`
4642: @*/
4643: PetscErrorCode TSComputeIFunctionLinear(TS ts, PetscReal t, Vec U, Vec Udot, Vec F, void *ctx)
4644: {
4645:   Mat A, B;

4647:   PetscFunctionBegin;
4648:   PetscCall(TSGetIJacobian(ts, &A, &B, NULL, NULL));
4649:   PetscCall(TSComputeIJacobian(ts, t, U, Udot, 1.0, A, B, PETSC_TRUE));
4650:   PetscCall(MatMult(A, Udot, F));
4651:   PetscFunctionReturn(PETSC_SUCCESS);
4652: }

4654: /*@C
4655:   TSComputeIJacobianConstant - Reuses the matrix previously computed with the provided `TSIJacobianFn` for a semi-implicit DAE or ODE

4657:   Collective

4659:   Input Parameters:
4660: + ts    - time stepping context
4661: . t     - time at which to evaluate
4662: . U     - state at which to evaluate
4663: . Udot  - time derivative of state vector
4664: . shift - shift to apply
4665: - ctx   - context

4667:   Output Parameters:
4668: + A - pointer to operator
4669: - B - pointer to matrix from which the preconditioner is built (often `A`)

4671:   Level: advanced

4673:   Notes:
4674:   This function is intended to be passed to `TSSetIJacobian()` to evaluate the Jacobian for linear time-independent problems.

4676:   It is only appropriate for problems of the form

4678:   $$
4679:   M \dot{U} = F(U,t)
4680:   $$

4682:   where M is constant and F is non-stiff.  The user must pass M to `TSSetIJacobian()`.  The current implementation only
4683:   works with IMEX time integration methods such as `TSROSW` and `TSARKIMEX`, since there is no support for de-constructing
4684:   an implicit operator of the form

4686:   $$
4687:   shift*M + J
4688:   $$

4690:   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
4691:   a copy of M or reassemble it when requested.

4693: .seealso: [](ch_ts), `TS`, `TSROSW`, `TSARKIMEX`, `TSSetIFunction()`, `TSSetIJacobian()`, `TSComputeIFunctionLinear()`
4694: @*/
4695: PetscErrorCode TSComputeIJacobianConstant(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat A, Mat B, void *ctx)
4696: {
4697:   PetscFunctionBegin;
4698:   PetscCall(MatScale(A, shift / ts->ijacobian.shift));
4699:   ts->ijacobian.shift = shift;
4700:   PetscFunctionReturn(PETSC_SUCCESS);
4701: }

4703: /*@
4704:   TSGetEquationType - Gets the type of the equation that `TS` is solving.

4706:   Not Collective

4708:   Input Parameter:
4709: . ts - the `TS` context

4711:   Output Parameter:
4712: . equation_type - see `TSEquationType`

4714:   Level: beginner

4716: .seealso: [](ch_ts), `TS`, `TSSetEquationType()`, `TSEquationType`
4717: @*/
4718: PetscErrorCode TSGetEquationType(TS ts, TSEquationType *equation_type)
4719: {
4720:   PetscFunctionBegin;
4722:   PetscAssertPointer(equation_type, 2);
4723:   *equation_type = ts->equation_type;
4724:   PetscFunctionReturn(PETSC_SUCCESS);
4725: }

4727: /*@
4728:   TSSetEquationType - Sets the type of the equation that `TS` is solving.

4730:   Not Collective

4732:   Input Parameters:
4733: + ts            - the `TS` context
4734: - equation_type - see `TSEquationType`

4736:   Level: advanced

4738: .seealso: [](ch_ts), `TS`, `TSGetEquationType()`, `TSEquationType`
4739: @*/
4740: PetscErrorCode TSSetEquationType(TS ts, TSEquationType equation_type)
4741: {
4742:   PetscFunctionBegin;
4744:   ts->equation_type = equation_type;
4745:   PetscFunctionReturn(PETSC_SUCCESS);
4746: }

4748: /*@
4749:   TSGetConvergedReason - Gets the reason the `TS` iteration was stopped.

4751:   Not Collective

4753:   Input Parameter:
4754: . ts - the `TS` context

4756:   Output Parameter:
4757: . reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4758:             manual pages for the individual convergence tests for complete lists

4760:   Level: beginner

4762:   Note:
4763:   Can only be called after the call to `TSSolve()` is complete.

4765: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4766: @*/
4767: PetscErrorCode TSGetConvergedReason(TS ts, TSConvergedReason *reason)
4768: {
4769:   PetscFunctionBegin;
4771:   PetscAssertPointer(reason, 2);
4772:   *reason = ts->reason;
4773:   PetscFunctionReturn(PETSC_SUCCESS);
4774: }

4776: /*@
4777:   TSSetConvergedReason - Sets the reason for handling the convergence of `TSSolve()`.

4779:   Logically Collective; reason must contain common value

4781:   Input Parameters:
4782: + ts     - the `TS` context
4783: - reason - negative value indicates diverged, positive value converged, see `TSConvergedReason` or the
4784:             manual pages for the individual convergence tests for complete lists

4786:   Level: advanced

4788:   Note:
4789:   Can only be called while `TSSolve()` is active.

4791: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4792: @*/
4793: PetscErrorCode TSSetConvergedReason(TS ts, TSConvergedReason reason)
4794: {
4795:   PetscFunctionBegin;
4797:   ts->reason = reason;
4798:   PetscFunctionReturn(PETSC_SUCCESS);
4799: }

4801: /*@
4802:   TSGetSolveTime - Gets the time after a call to `TSSolve()`

4804:   Not Collective

4806:   Input Parameter:
4807: . ts - the `TS` context

4809:   Output Parameter:
4810: . ftime - the final time. This time corresponds to the final time set with `TSSetMaxTime()`

4812:   Level: beginner

4814:   Note:
4815:   Can only be called after the call to `TSSolve()` is complete.

4817: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSConvergedReason`
4818: @*/
4819: PetscErrorCode TSGetSolveTime(TS ts, PetscReal *ftime)
4820: {
4821:   PetscFunctionBegin;
4823:   PetscAssertPointer(ftime, 2);
4824:   *ftime = ts->solvetime;
4825:   PetscFunctionReturn(PETSC_SUCCESS);
4826: }

4828: /*@
4829:   TSGetSNESIterations - Gets the total number of nonlinear iterations
4830:   used by the time integrator.

4832:   Not Collective

4834:   Input Parameter:
4835: . ts - `TS` context

4837:   Output Parameter:
4838: . nits - number of nonlinear iterations

4840:   Level: intermediate

4842:   Note:
4843:   This counter is reset to zero for each successive call to `TSSolve()`.

4845: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetKSPIterations()`
4846: @*/
4847: PetscErrorCode TSGetSNESIterations(TS ts, PetscInt *nits)
4848: {
4849:   PetscFunctionBegin;
4851:   PetscAssertPointer(nits, 2);
4852:   *nits = ts->snes_its;
4853:   PetscFunctionReturn(PETSC_SUCCESS);
4854: }

4856: /*@
4857:   TSGetKSPIterations - Gets the total number of linear iterations
4858:   used by the time integrator.

4860:   Not Collective

4862:   Input Parameter:
4863: . ts - `TS` context

4865:   Output Parameter:
4866: . lits - number of linear iterations

4868:   Level: intermediate

4870:   Note:
4871:   This counter is reset to zero for each successive call to `TSSolve()`.

4873: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`
4874: @*/
4875: PetscErrorCode TSGetKSPIterations(TS ts, PetscInt *lits)
4876: {
4877:   PetscFunctionBegin;
4879:   PetscAssertPointer(lits, 2);
4880:   *lits = ts->ksp_its;
4881:   PetscFunctionReturn(PETSC_SUCCESS);
4882: }

4884: /*@
4885:   TSGetStepRejections - Gets the total number of rejected steps.

4887:   Not Collective

4889:   Input Parameter:
4890: . ts - `TS` context

4892:   Output Parameter:
4893: . rejects - number of steps rejected

4895:   Level: intermediate

4897:   Note:
4898:   This counter is reset to zero for each successive call to `TSSolve()`.

4900: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetSNESFailures()`, `TSSetMaxSNESFailures()`, `TSSetErrorIfStepFails()`
4901: @*/
4902: PetscErrorCode TSGetStepRejections(TS ts, PetscInt *rejects)
4903: {
4904:   PetscFunctionBegin;
4906:   PetscAssertPointer(rejects, 2);
4907:   *rejects = ts->reject;
4908:   PetscFunctionReturn(PETSC_SUCCESS);
4909: }

4911: /*@
4912:   TSGetSNESFailures - Gets the total number of failed `SNES` solves in a `TS`

4914:   Not Collective

4916:   Input Parameter:
4917: . ts - `TS` context

4919:   Output Parameter:
4920: . fails - number of failed nonlinear solves

4922:   Level: intermediate

4924:   Note:
4925:   This counter is reset to zero for each successive call to `TSSolve()`.

4927: .seealso: [](ch_ts), `TS`, `TSSolve()`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSSetMaxSNESFailures()`
4928: @*/
4929: PetscErrorCode TSGetSNESFailures(TS ts, PetscInt *fails)
4930: {
4931:   PetscFunctionBegin;
4933:   PetscAssertPointer(fails, 2);
4934:   *fails = ts->num_snes_failures;
4935:   PetscFunctionReturn(PETSC_SUCCESS);
4936: }

4938: /*@
4939:   TSSetMaxStepRejections - Sets the maximum number of step rejections before a time step fails

4941:   Not Collective

4943:   Input Parameters:
4944: + ts      - `TS` context
4945: - rejects - maximum number of rejected steps, pass `PETSC_UNLIMITED` for unlimited

4947:   Options Database Key:
4948: . -ts_max_reject - Maximum number of step rejections before a step fails

4950:   Level: intermediate

4952:   Developer Note:
4953:   The options database name is incorrect.

4955: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxSNESFailures()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSSetErrorIfStepFails()`, `TSGetConvergedReason()`
4956: @*/
4957: PetscErrorCode TSSetMaxStepRejections(TS ts, PetscInt rejects)
4958: {
4959:   PetscFunctionBegin;
4961:   if (rejects == PETSC_UNLIMITED || rejects == -1) {
4962:     ts->max_reject = PETSC_UNLIMITED;
4963:   } else {
4964:     PetscCheck(rejects >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of rejections");
4965:     ts->max_reject = rejects;
4966:   }
4967:   PetscFunctionReturn(PETSC_SUCCESS);
4968: }

4970: /*@
4971:   TSSetMaxSNESFailures - Sets the maximum number of failed `SNES` solves

4973:   Not Collective

4975:   Input Parameters:
4976: + ts    - `TS` context
4977: - fails - maximum number of failed nonlinear solves, pass `PETSC_UNLIMITED` to allow any number of failures.

4979:   Options Database Key:
4980: . -ts_max_snes_failures - Maximum number of nonlinear solve failures

4982:   Level: intermediate

4984: .seealso: [](ch_ts), `TS`, `SNES`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `SNESGetConvergedReason()`, `TSGetConvergedReason()`
4985: @*/
4986: PetscErrorCode TSSetMaxSNESFailures(TS ts, PetscInt fails)
4987: {
4988:   PetscFunctionBegin;
4990:   if (fails == PETSC_UNLIMITED || fails == -1) {
4991:     ts->max_snes_failures = PETSC_UNLIMITED;
4992:   } else {
4993:     PetscCheck(fails >= 0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Cannot have a negative maximum number of failures");
4994:     ts->max_snes_failures = fails;
4995:   }
4996:   PetscFunctionReturn(PETSC_SUCCESS);
4997: }

4999: /*@
5000:   TSSetErrorIfStepFails - Immediately error if no step succeeds during `TSSolve()`

5002:   Not Collective

5004:   Input Parameters:
5005: + ts  - `TS` context
5006: - err - `PETSC_TRUE` to error if no step succeeds, `PETSC_FALSE` to return without failure

5008:   Options Database Key:
5009: . -ts_error_if_step_fails - Error if no step succeeds

5011:   Level: intermediate

5013: .seealso: [](ch_ts), `TS`, `TSGetSNESIterations()`, `TSGetKSPIterations()`, `TSSetMaxStepRejections()`, `TSGetStepRejections()`, `TSGetSNESFailures()`, `TSGetConvergedReason()`
5014: @*/
5015: PetscErrorCode TSSetErrorIfStepFails(TS ts, PetscBool err)
5016: {
5017:   PetscFunctionBegin;
5019:   ts->errorifstepfailed = err;
5020:   PetscFunctionReturn(PETSC_SUCCESS);
5021: }

5023: /*@
5024:   TSGetAdapt - Get the adaptive controller context for the current method

5026:   Collective if controller has not yet been created

5028:   Input Parameter:
5029: . ts - time stepping context

5031:   Output Parameter:
5032: . adapt - adaptive controller

5034:   Level: intermediate

5036: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSAdaptSetType()`, `TSAdaptChoose()`
5037: @*/
5038: PetscErrorCode TSGetAdapt(TS ts, TSAdapt *adapt)
5039: {
5040:   PetscFunctionBegin;
5042:   PetscAssertPointer(adapt, 2);
5043:   if (!ts->adapt) {
5044:     PetscCall(TSAdaptCreate(PetscObjectComm((PetscObject)ts), &ts->adapt));
5045:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)ts->adapt, (PetscObject)ts, 1));
5046:   }
5047:   *adapt = ts->adapt;
5048:   PetscFunctionReturn(PETSC_SUCCESS);
5049: }

5051: /*@
5052:   TSSetTolerances - Set tolerances for local truncation error when using an adaptive controller

5054:   Logically Collective

5056:   Input Parameters:
5057: + ts    - time integration context
5058: . atol  - scalar absolute tolerances
5059: . vatol - vector of absolute tolerances or `NULL`, used in preference to `atol` if present
5060: . rtol  - scalar relative tolerances
5061: - vrtol - vector of relative tolerances or `NULL`, used in preference to `rtol` if present

5063:   Options Database Keys:
5064: + -ts_rtol <rtol> - relative tolerance for local truncation error
5065: - -ts_atol <atol> - Absolute tolerance for local truncation error

5067:   Level: beginner

5069:   Notes:
5070:   `PETSC_CURRENT` or `PETSC_DETERMINE` may be used for `atol` or `rtol` to indicate the current value
5071:   or the default value from when the object's type was set.

5073:   With PETSc's implicit schemes for DAE problems, the calculation of the local truncation error
5074:   (LTE) includes both the differential and the algebraic variables. If one wants the LTE to be
5075:   computed only for the differential or the algebraic part then this can be done using the vector of
5076:   tolerances vatol. For example, by setting the tolerance vector with the desired tolerance for the
5077:   differential part and infinity for the algebraic part, the LTE calculation will include only the
5078:   differential variables.

5080:   Fortran Note:
5081:   Use `PETSC_CURRENT_INTEGER` or `PETSC_DETERMINE_INTEGER`.

5083: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSGetTolerances()`
5084: @*/
5085: PetscErrorCode TSSetTolerances(TS ts, PetscReal atol, Vec vatol, PetscReal rtol, Vec vrtol)
5086: {
5087:   PetscFunctionBegin;
5088:   if (atol == (PetscReal)PETSC_DETERMINE) {
5089:     ts->atol = ts->default_atol;
5090:   } else if (atol != (PetscReal)PETSC_CURRENT) {
5091:     PetscCheck(atol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Absolute tolerance %g must be non-negative", (double)atol);
5092:     ts->atol = atol;
5093:   }

5095:   if (vatol) {
5096:     PetscCall(PetscObjectReference((PetscObject)vatol));
5097:     PetscCall(VecDestroy(&ts->vatol));
5098:     ts->vatol = vatol;
5099:   }

5101:   if (rtol == (PetscReal)PETSC_DETERMINE) {
5102:     ts->rtol = ts->default_rtol;
5103:   } else if (rtol != (PetscReal)PETSC_CURRENT) {
5104:     PetscCheck(rtol >= 0.0, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_OUTOFRANGE, "Relative tolerance %g must be non-negative", (double)rtol);
5105:     ts->rtol = rtol;
5106:   }

5108:   if (vrtol) {
5109:     PetscCall(PetscObjectReference((PetscObject)vrtol));
5110:     PetscCall(VecDestroy(&ts->vrtol));
5111:     ts->vrtol = vrtol;
5112:   }
5113:   PetscFunctionReturn(PETSC_SUCCESS);
5114: }

5116: /*@
5117:   TSGetTolerances - Get tolerances for local truncation error when using adaptive controller

5119:   Logically Collective

5121:   Input Parameter:
5122: . ts - time integration context

5124:   Output Parameters:
5125: + atol  - scalar absolute tolerances, `NULL` to ignore
5126: . vatol - vector of absolute tolerances, `NULL` to ignore
5127: . rtol  - scalar relative tolerances, `NULL` to ignore
5128: - vrtol - vector of relative tolerances, `NULL` to ignore

5130:   Level: beginner

5132: .seealso: [](ch_ts), `TS`, `TSAdapt`, `TSErrorWeightedNorm()`, `TSSetTolerances()`
5133: @*/
5134: PetscErrorCode TSGetTolerances(TS ts, PetscReal *atol, Vec *vatol, PetscReal *rtol, Vec *vrtol)
5135: {
5136:   PetscFunctionBegin;
5137:   if (atol) *atol = ts->atol;
5138:   if (vatol) *vatol = ts->vatol;
5139:   if (rtol) *rtol = ts->rtol;
5140:   if (vrtol) *vrtol = ts->vrtol;
5141:   PetscFunctionReturn(PETSC_SUCCESS);
5142: }

5144: /*@
5145:   TSErrorWeightedNorm - compute a weighted norm of the difference between two state vectors based on supplied absolute and relative tolerances

5147:   Collective

5149:   Input Parameters:
5150: + ts        - time stepping context
5151: . U         - state vector, usually ts->vec_sol
5152: . Y         - state vector to be compared to U
5153: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5155:   Output Parameters:
5156: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5157: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5158: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5160:   Options Database Key:
5161: . -ts_adapt_wnormtype <wnormtype> - 2, INFINITY

5163:   Level: developer

5165: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedENorm()`
5166: @*/
5167: PetscErrorCode TSErrorWeightedNorm(TS ts, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5168: {
5169:   PetscInt norma_loc, norm_loc, normr_loc;

5171:   PetscFunctionBegin;
5173:   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));
5174:   if (wnormtype == NORM_2) {
5175:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5176:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5177:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5178:   }
5179:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5180:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5181:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5182:   PetscFunctionReturn(PETSC_SUCCESS);
5183: }

5185: /*@
5186:   TSErrorWeightedENorm - compute a weighted error norm based on supplied absolute and relative tolerances

5188:   Collective

5190:   Input Parameters:
5191: + ts        - time stepping context
5192: . E         - error vector
5193: . U         - state vector, usually ts->vec_sol
5194: . Y         - state vector, previous time step
5195: - wnormtype - norm type, either `NORM_2` or `NORM_INFINITY`

5197:   Output Parameters:
5198: + norm  - weighted norm, a value of 1.0 achieves a balance between absolute and relative tolerances
5199: . norma - weighted norm, a value of 1.0 means that the error meets the absolute tolerance set by the user
5200: - normr - weighted norm, a value of 1.0 means that the error meets the relative tolerance set by the user

5202:   Options Database Key:
5203: . -ts_adapt_wnormtype <wnormtype> - 2, INFINITY

5205:   Level: developer

5207: .seealso: [](ch_ts), `TS`, `VecErrorWeightedNorms()`, `TSErrorWeightedNorm()`
5208: @*/
5209: PetscErrorCode TSErrorWeightedENorm(TS ts, Vec E, Vec U, Vec Y, NormType wnormtype, PetscReal *norm, PetscReal *norma, PetscReal *normr)
5210: {
5211:   PetscInt norma_loc, norm_loc, normr_loc;

5213:   PetscFunctionBegin;
5215:   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));
5216:   if (wnormtype == NORM_2) {
5217:     if (norm_loc) *norm = PetscSqrtReal(PetscSqr(*norm) / norm_loc);
5218:     if (norma_loc) *norma = PetscSqrtReal(PetscSqr(*norma) / norma_loc);
5219:     if (normr_loc) *normr = PetscSqrtReal(PetscSqr(*normr) / normr_loc);
5220:   }
5221:   PetscCheck(!PetscIsInfOrNanScalar(*norm), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norm");
5222:   PetscCheck(!PetscIsInfOrNanScalar(*norma), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in norma");
5223:   PetscCheck(!PetscIsInfOrNanScalar(*normr), PetscObjectComm((PetscObject)ts), PETSC_ERR_FP, "Infinite or not-a-number generated in normr");
5224:   PetscFunctionReturn(PETSC_SUCCESS);
5225: }

5227: /*@
5228:   TSSetCFLTimeLocal - Set the local CFL constraint relative to forward Euler

5230:   Logically Collective

5232:   Input Parameters:
5233: + ts      - time stepping context
5234: - cfltime - maximum stable time step if using forward Euler (value can be different on each process)

5236:   Note:
5237:   After calling this function, the global CFL time can be obtained by calling TSGetCFLTime()

5239:   Level: intermediate

5241: .seealso: [](ch_ts), `TSGetCFLTime()`, `TSADAPTCFL`
5242: @*/
5243: PetscErrorCode TSSetCFLTimeLocal(TS ts, PetscReal cfltime)
5244: {
5245:   PetscFunctionBegin;
5247:   ts->cfltime_local = cfltime;
5248:   ts->cfltime       = -1.;
5249:   PetscFunctionReturn(PETSC_SUCCESS);
5250: }

5252: /*@
5253:   TSGetCFLTime - Get the maximum stable time step according to CFL criteria applied to forward Euler

5255:   Collective

5257:   Input Parameter:
5258: . ts - time stepping context

5260:   Output Parameter:
5261: . cfltime - maximum stable time step for forward Euler

5263:   Level: advanced

5265: .seealso: [](ch_ts), `TSSetCFLTimeLocal()`
5266: @*/
5267: PetscErrorCode TSGetCFLTime(TS ts, PetscReal *cfltime)
5268: {
5269:   PetscFunctionBegin;
5270:   if (ts->cfltime < 0) PetscCallMPI(MPIU_Allreduce(&ts->cfltime_local, &ts->cfltime, 1, MPIU_REAL, MPIU_MIN, PetscObjectComm((PetscObject)ts)));
5271:   *cfltime = ts->cfltime;
5272:   PetscFunctionReturn(PETSC_SUCCESS);
5273: }

5275: /*@
5276:   TSVISetVariableBounds - Sets the lower and upper bounds for the solution vector. xl <= x <= xu

5278:   Input Parameters:
5279: + ts - the `TS` context.
5280: . xl - lower bound.
5281: - xu - upper bound.

5283:   Level: advanced

5285:   Note:
5286:   If this routine is not called then the lower and upper bounds are set to
5287:   `PETSC_NINFINITY` and `PETSC_INFINITY` respectively during `SNESSetUp()`.

5289: .seealso: [](ch_ts), `TS`
5290: @*/
5291: PetscErrorCode TSVISetVariableBounds(TS ts, Vec xl, Vec xu)
5292: {
5293:   SNES snes;

5295:   PetscFunctionBegin;
5296:   PetscCall(TSGetSNES(ts, &snes));
5297:   PetscCall(SNESVISetVariableBounds(snes, xl, xu));
5298:   PetscFunctionReturn(PETSC_SUCCESS);
5299: }

5301: /*@
5302:   TSComputeLinearStability - computes the linear stability function at a point

5304:   Collective

5306:   Input Parameters:
5307: + ts - the `TS` context
5308: . xr - real part of input argument
5309: - xi - imaginary part of input argument

5311:   Output Parameters:
5312: + yr - real part of function value
5313: - yi - imaginary part of function value

5315:   Level: developer

5317: .seealso: [](ch_ts), `TS`, `TSSetRHSFunction()`, `TSComputeIFunction()`
5318: @*/
5319: PetscErrorCode TSComputeLinearStability(TS ts, PetscReal xr, PetscReal xi, PetscReal *yr, PetscReal *yi)
5320: {
5321:   PetscFunctionBegin;
5323:   PetscUseTypeMethod(ts, linearstability, xr, xi, yr, yi);
5324:   PetscFunctionReturn(PETSC_SUCCESS);
5325: }

5327: /*@
5328:   TSRestartStep - Flags the solver to restart the next step

5330:   Collective

5332:   Input Parameter:
5333: . ts - the `TS` context obtained from `TSCreate()`

5335:   Level: advanced

5337:   Notes:
5338:   Multistep methods like `TSBDF` or Runge-Kutta methods with FSAL property require restarting the solver in the event of
5339:   discontinuities. These discontinuities may be introduced as a consequence of explicitly modifications to the solution
5340:   vector (which PETSc attempts to detect and handle) or problem coefficients (which PETSc is not able to detect). For
5341:   the sake of correctness and maximum safety, users are expected to call `TSRestart()` whenever they introduce
5342:   discontinuities in callback routines (e.g. prestep and poststep routines, or implicit/rhs function routines with
5343:   discontinuous source terms).

5345: .seealso: [](ch_ts), `TS`, `TSBDF`, `TSSolve()`, `TSSetPreStep()`, `TSSetPostStep()`
5346: @*/
5347: PetscErrorCode TSRestartStep(TS ts)
5348: {
5349:   PetscFunctionBegin;
5351:   ts->steprestart = PETSC_TRUE;
5352:   PetscFunctionReturn(PETSC_SUCCESS);
5353: }

5355: /*@
5356:   TSRollBack - Rolls back one time step

5358:   Collective

5360:   Input Parameter:
5361: . ts - the `TS` context obtained from `TSCreate()`

5363:   Level: advanced

5365: .seealso: [](ch_ts), `TS`, `TSGetStepRollBack()`, `TSCreate()`, `TSSetUp()`, `TSDestroy()`, `TSSolve()`, `TSSetPreStep()`, `TSSetPreStage()`, `TSInterpolate()`
5366: @*/
5367: PetscErrorCode TSRollBack(TS ts)
5368: {
5369:   PetscFunctionBegin;
5371:   PetscCheck(!ts->steprollback, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONGSTATE, "TSRollBack already called");
5372:   PetscTryTypeMethod(ts, rollback);
5373:   PetscCall(VecCopy(ts->vec_sol0, ts->vec_sol));
5374:   ts->time_step  = ts->ptime - ts->ptime_prev;
5375:   ts->ptime      = ts->ptime_prev;
5376:   ts->ptime_prev = ts->ptime_prev_rollback;
5377:   ts->steps--;
5378:   ts->steprollback = PETSC_TRUE;
5379:   PetscFunctionReturn(PETSC_SUCCESS);
5380: }

5382: /*@
5383:   TSGetStepRollBack - Get the internal flag indicating if you are rolling back a step

5385:   Not collective

5387:   Input Parameter:
5388: . ts - the `TS` context obtained from `TSCreate()`

5390:   Output Parameter:
5391: . flg - the rollback flag

5393:   Level: advanced

5395: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSRollBack()`
5396: @*/
5397: PetscErrorCode TSGetStepRollBack(TS ts, PetscBool *flg)
5398: {
5399:   PetscFunctionBegin;
5401:   PetscAssertPointer(flg, 2);
5402:   *flg = ts->steprollback;
5403:   PetscFunctionReturn(PETSC_SUCCESS);
5404: }

5406: /*@
5407:   TSGetStepResize - Get the internal flag indicating if the current step is after a resize.

5409:   Not collective

5411:   Input Parameter:
5412: . ts - the `TS` context obtained from `TSCreate()`

5414:   Output Parameter:
5415: . flg - the resize flag

5417:   Level: advanced

5419: .seealso: [](ch_ts), `TS`, `TSCreate()`, `TSSetResize()`
5420: @*/
5421: PetscErrorCode TSGetStepResize(TS ts, PetscBool *flg)
5422: {
5423:   PetscFunctionBegin;
5425:   PetscAssertPointer(flg, 2);
5426:   *flg = ts->stepresize;
5427:   PetscFunctionReturn(PETSC_SUCCESS);
5428: }

5430: /*@
5431:   TSGetStages - Get the number of stages and stage values

5433:   Input Parameter:
5434: . ts - the `TS` context obtained from `TSCreate()`

5436:   Output Parameters:
5437: + ns - the number of stages
5438: - Y  - the current stage vectors

5440:   Level: advanced

5442:   Note:
5443:   Both `ns` and `Y` can be `NULL`.

5445: .seealso: [](ch_ts), `TS`, `TSCreate()`
5446: @*/
5447: PetscErrorCode TSGetStages(TS ts, PetscInt *ns, Vec **Y)
5448: {
5449:   PetscFunctionBegin;
5451:   if (ns) PetscAssertPointer(ns, 2);
5452:   if (Y) PetscAssertPointer(Y, 3);
5453:   if (!ts->ops->getstages) {
5454:     if (ns) *ns = 0;
5455:     if (Y) *Y = NULL;
5456:   } else PetscUseTypeMethod(ts, getstages, ns, Y);
5457:   PetscFunctionReturn(PETSC_SUCCESS);
5458: }

5460: /*@C
5461:   TSComputeIJacobianDefaultColor - Computes the Jacobian using finite differences and coloring to exploit matrix sparsity.

5463:   Collective

5465:   Input Parameters:
5466: + ts    - the `TS` context
5467: . t     - current timestep
5468: . U     - state vector
5469: . Udot  - time derivative of state vector
5470: . shift - shift to apply, see note below
5471: - ctx   - an optional user context

5473:   Output Parameters:
5474: + J - Jacobian matrix (not altered in this routine)
5475: - B - newly computed Jacobian matrix to use with preconditioner (generally the same as `J`)

5477:   Level: intermediate

5479:   Notes:
5480:   If F(t,U,Udot)=0 is the DAE, the required Jacobian is

5482:   dF/dU + shift*dF/dUdot

5484:   Most users should not need to explicitly call this routine, as it
5485:   is used internally within the nonlinear solvers.

5487:   This will first try to get the coloring from the `DM`.  If the `DM` type has no coloring
5488:   routine, then it will try to get the coloring from the matrix.  This requires that the
5489:   matrix have nonzero entries precomputed.

5491: .seealso: [](ch_ts), `TS`, `TSSetIJacobian()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
5492: @*/
5493: PetscErrorCode TSComputeIJacobianDefaultColor(TS ts, PetscReal t, Vec U, Vec Udot, PetscReal shift, Mat J, Mat B, void *ctx)
5494: {
5495:   SNES          snes;
5496:   MatFDColoring color;
5497:   PetscBool     hascolor, matcolor = PETSC_FALSE;

5499:   PetscFunctionBegin;
5500:   PetscCall(PetscOptionsGetBool(((PetscObject)ts)->options, ((PetscObject)ts)->prefix, "-ts_fd_color_use_mat", &matcolor, NULL));
5501:   PetscCall(PetscObjectQuery((PetscObject)B, "TSMatFDColoring", (PetscObject *)&color));
5502:   if (!color) {
5503:     DM         dm;
5504:     ISColoring iscoloring;

5506:     PetscCall(TSGetDM(ts, &dm));
5507:     PetscCall(DMHasColoring(dm, &hascolor));
5508:     if (hascolor && !matcolor) {
5509:       PetscCall(DMCreateColoring(dm, IS_COLORING_GLOBAL, &iscoloring));
5510:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5511:       PetscCall(MatFDColoringSetFunction(color, (PetscErrorCode (*)(void))SNESTSFormFunction, (void *)ts));
5512:       PetscCall(MatFDColoringSetFromOptions(color));
5513:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5514:       PetscCall(ISColoringDestroy(&iscoloring));
5515:     } else {
5516:       MatColoring mc;

5518:       PetscCall(MatColoringCreate(B, &mc));
5519:       PetscCall(MatColoringSetDistance(mc, 2));
5520:       PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
5521:       PetscCall(MatColoringSetFromOptions(mc));
5522:       PetscCall(MatColoringApply(mc, &iscoloring));
5523:       PetscCall(MatColoringDestroy(&mc));
5524:       PetscCall(MatFDColoringCreate(B, iscoloring, &color));
5525:       PetscCall(MatFDColoringSetFunction(color, (PetscErrorCode (*)(void))SNESTSFormFunction, (void *)ts));
5526:       PetscCall(MatFDColoringSetFromOptions(color));
5527:       PetscCall(MatFDColoringSetUp(B, iscoloring, color));
5528:       PetscCall(ISColoringDestroy(&iscoloring));
5529:     }
5530:     PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)color));
5531:     PetscCall(PetscObjectDereference((PetscObject)color));
5532:   }
5533:   PetscCall(TSGetSNES(ts, &snes));
5534:   PetscCall(MatFDColoringApply(B, color, U, snes));
5535:   if (J != B) {
5536:     PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
5537:     PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));
5538:   }
5539:   PetscFunctionReturn(PETSC_SUCCESS);
5540: }

5542: /*@C
5543:   TSSetFunctionDomainError - Set a function that tests if the current state vector is valid

5545:   Input Parameters:
5546: + ts   - the `TS` context
5547: - func - function called within `TSFunctionDomainError()`

5549:   Calling sequence of `func`:
5550: + ts     - the `TS` context
5551: . time   - the current time (of the stage)
5552: . state  - the state to check if it is valid
5553: - accept - (output parameter) `PETSC_FALSE` if the state is not acceptable, `PETSC_TRUE` if acceptable

5555:   Level: intermediate

5557:   Notes:
5558:   If an implicit ODE solver is being used then, in addition to providing this routine, the
5559:   user's code should call `SNESSetFunctionDomainError()` when domain errors occur during
5560:   function evaluations where the functions are provided by `TSSetIFunction()` or `TSSetRHSFunction()`.
5561:   Use `TSGetSNES()` to obtain the `SNES` object

5563:   Developer Notes:
5564:   The naming of this function is inconsistent with the `SNESSetFunctionDomainError()`
5565:   since one takes a function pointer and the other does not.

5567: .seealso: [](ch_ts), `TSAdaptCheckStage()`, `TSFunctionDomainError()`, `SNESSetFunctionDomainError()`, `TSGetSNES()`
5568: @*/
5569: PetscErrorCode TSSetFunctionDomainError(TS ts, PetscErrorCode (*func)(TS ts, PetscReal time, Vec state, PetscBool *accept))
5570: {
5571:   PetscFunctionBegin;
5573:   ts->functiondomainerror = func;
5574:   PetscFunctionReturn(PETSC_SUCCESS);
5575: }

5577: /*@
5578:   TSFunctionDomainError - Checks if the current state is valid

5580:   Input Parameters:
5581: + ts        - the `TS` context
5582: . stagetime - time of the simulation
5583: - Y         - state vector to check.

5585:   Output Parameter:
5586: . accept - Set to `PETSC_FALSE` if the current state vector is valid.

5588:   Level: developer

5590:   Note:
5591:   This function is called by the `TS` integration routines and calls the user provided function (set with `TSSetFunctionDomainError()`)
5592:   to check if the current state is valid.

5594: .seealso: [](ch_ts), `TS`, `TSSetFunctionDomainError()`
5595: @*/
5596: PetscErrorCode TSFunctionDomainError(TS ts, PetscReal stagetime, Vec Y, PetscBool *accept)
5597: {
5598:   PetscFunctionBegin;
5600:   *accept = PETSC_TRUE;
5601:   if (ts->functiondomainerror) PetscCall((*ts->functiondomainerror)(ts, stagetime, Y, accept));
5602:   PetscFunctionReturn(PETSC_SUCCESS);
5603: }

5605: /*@
5606:   TSClone - This function clones a time step `TS` object.

5608:   Collective

5610:   Input Parameter:
5611: . tsin - The input `TS`

5613:   Output Parameter:
5614: . tsout - The output `TS` (cloned)

5616:   Level: developer

5618:   Notes:
5619:   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.
5620:   It will likely be replaced in the future with a mechanism of switching methods on the fly.

5622:   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
5623: .vb
5624:  SNES snes_dup = NULL;
5625:  TSGetSNES(ts,&snes_dup);
5626:  TSSetSNES(ts,snes_dup);
5627: .ve

5629: .seealso: [](ch_ts), `TS`, `SNES`, `TSCreate()`, `TSSetType()`, `TSSetUp()`, `TSDestroy()`, `TSSetProblemType()`
5630: @*/
5631: PetscErrorCode TSClone(TS tsin, TS *tsout)
5632: {
5633:   TS     t;
5634:   SNES   snes_start;
5635:   DM     dm;
5636:   TSType type;

5638:   PetscFunctionBegin;
5639:   PetscAssertPointer(tsin, 1);
5640:   *tsout = NULL;

5642:   PetscCall(PetscHeaderCreate(t, TS_CLASSID, "TS", "Time stepping", "TS", PetscObjectComm((PetscObject)tsin), TSDestroy, TSView));

5644:   /* General TS description */
5645:   t->numbermonitors    = 0;
5646:   t->monitorFrequency  = 1;
5647:   t->setupcalled       = 0;
5648:   t->ksp_its           = 0;
5649:   t->snes_its          = 0;
5650:   t->nwork             = 0;
5651:   t->rhsjacobian.time  = PETSC_MIN_REAL;
5652:   t->rhsjacobian.scale = 1.;
5653:   t->ijacobian.shift   = 1.;

5655:   PetscCall(TSGetSNES(tsin, &snes_start));
5656:   PetscCall(TSSetSNES(t, snes_start));

5658:   PetscCall(TSGetDM(tsin, &dm));
5659:   PetscCall(TSSetDM(t, dm));

5661:   t->adapt = tsin->adapt;
5662:   PetscCall(PetscObjectReference((PetscObject)t->adapt));

5664:   t->trajectory = tsin->trajectory;
5665:   PetscCall(PetscObjectReference((PetscObject)t->trajectory));

5667:   t->event = tsin->event;
5668:   if (t->event) t->event->refct++;

5670:   t->problem_type      = tsin->problem_type;
5671:   t->ptime             = tsin->ptime;
5672:   t->ptime_prev        = tsin->ptime_prev;
5673:   t->time_step         = tsin->time_step;
5674:   t->max_time          = tsin->max_time;
5675:   t->steps             = tsin->steps;
5676:   t->max_steps         = tsin->max_steps;
5677:   t->equation_type     = tsin->equation_type;
5678:   t->atol              = tsin->atol;
5679:   t->rtol              = tsin->rtol;
5680:   t->max_snes_failures = tsin->max_snes_failures;
5681:   t->max_reject        = tsin->max_reject;
5682:   t->errorifstepfailed = tsin->errorifstepfailed;

5684:   PetscCall(TSGetType(tsin, &type));
5685:   PetscCall(TSSetType(t, type));

5687:   t->vec_sol = NULL;

5689:   t->cfltime          = tsin->cfltime;
5690:   t->cfltime_local    = tsin->cfltime_local;
5691:   t->exact_final_time = tsin->exact_final_time;

5693:   t->ops[0] = tsin->ops[0];

5695:   if (((PetscObject)tsin)->fortran_func_pointers) {
5696:     PetscInt i;
5697:     PetscCall(PetscMalloc((10) * sizeof(void (*)(void)), &((PetscObject)t)->fortran_func_pointers));
5698:     for (i = 0; i < 10; i++) ((PetscObject)t)->fortran_func_pointers[i] = ((PetscObject)tsin)->fortran_func_pointers[i];
5699:   }
5700:   *tsout = t;
5701:   PetscFunctionReturn(PETSC_SUCCESS);
5702: }

5704: static PetscErrorCode RHSWrapperFunction_TSRHSJacobianTest(void *ctx, Vec x, Vec y)
5705: {
5706:   TS ts = (TS)ctx;

5708:   PetscFunctionBegin;
5709:   PetscCall(TSComputeRHSFunction(ts, 0, x, y));
5710:   PetscFunctionReturn(PETSC_SUCCESS);
5711: }

5713: /*@
5714:   TSRHSJacobianTest - Compares the multiply routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5716:   Logically Collective

5718:   Input Parameter:
5719: . ts - the time stepping routine

5721:   Output Parameter:
5722: . flg - `PETSC_TRUE` if the multiply is likely correct

5724:   Options Database Key:
5725: . -ts_rhs_jacobian_test_mult -mat_shell_test_mult_view - run the test at each timestep of the integrator

5727:   Level: advanced

5729:   Note:
5730:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5732: .seealso: [](ch_ts), `TS`, `Mat`, `MATSHELL`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTestTranspose()`
5733: @*/
5734: PetscErrorCode TSRHSJacobianTest(TS ts, PetscBool *flg)
5735: {
5736:   Mat              J, B;
5737:   TSRHSJacobianFn *func;
5738:   void            *ctx;

5740:   PetscFunctionBegin;
5741:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5742:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5743:   PetscCall(MatShellTestMult(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5744:   PetscFunctionReturn(PETSC_SUCCESS);
5745: }

5747: /*@
5748:   TSRHSJacobianTestTranspose - Compares the multiply transpose routine provided to the `MATSHELL` with differencing on the `TS` given RHS function.

5750:   Logically Collective

5752:   Input Parameter:
5753: . ts - the time stepping routine

5755:   Output Parameter:
5756: . flg - `PETSC_TRUE` if the multiply is likely correct

5758:   Options Database Key:
5759: . -ts_rhs_jacobian_test_mult_transpose -mat_shell_test_mult_transpose_view - run the test at each timestep of the integrator

5761:   Level: advanced

5763:   Notes:
5764:   This only works for problems defined using `TSSetRHSFunction()` and Jacobian NOT `TSSetIFunction()` and Jacobian

5766: .seealso: [](ch_ts), `TS`, `Mat`, `MatCreateShell()`, `MatShellGetContext()`, `MatShellGetOperation()`, `MatShellTestMultTranspose()`, `TSRHSJacobianTest()`
5767: @*/
5768: PetscErrorCode TSRHSJacobianTestTranspose(TS ts, PetscBool *flg)
5769: {
5770:   Mat              J, B;
5771:   void            *ctx;
5772:   TSRHSJacobianFn *func;

5774:   PetscFunctionBegin;
5775:   PetscCall(TSGetRHSJacobian(ts, &J, &B, &func, &ctx));
5776:   PetscCall((*func)(ts, 0.0, ts->vec_sol, J, B, ctx));
5777:   PetscCall(MatShellTestMultTranspose(J, RHSWrapperFunction_TSRHSJacobianTest, ts->vec_sol, ts, flg));
5778:   PetscFunctionReturn(PETSC_SUCCESS);
5779: }

5781: /*@
5782:   TSSetUseSplitRHSFunction - Use the split RHSFunction when a multirate method is used.

5784:   Logically Collective

5786:   Input Parameters:
5787: + ts                   - timestepping context
5788: - use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5790:   Options Database Key:
5791: . -ts_use_splitrhsfunction - <true,false>

5793:   Level: intermediate

5795:   Note:
5796:   This is only for multirate methods

5798: .seealso: [](ch_ts), `TS`, `TSGetUseSplitRHSFunction()`
5799: @*/
5800: PetscErrorCode TSSetUseSplitRHSFunction(TS ts, PetscBool use_splitrhsfunction)
5801: {
5802:   PetscFunctionBegin;
5804:   ts->use_splitrhsfunction = use_splitrhsfunction;
5805:   PetscFunctionReturn(PETSC_SUCCESS);
5806: }

5808: /*@
5809:   TSGetUseSplitRHSFunction - Gets whether to use the split RHSFunction when a multirate method is used.

5811:   Not Collective

5813:   Input Parameter:
5814: . ts - timestepping context

5816:   Output Parameter:
5817: . use_splitrhsfunction - `PETSC_TRUE` indicates that the split RHSFunction will be used

5819:   Level: intermediate

5821: .seealso: [](ch_ts), `TS`, `TSSetUseSplitRHSFunction()`
5822: @*/
5823: PetscErrorCode TSGetUseSplitRHSFunction(TS ts, PetscBool *use_splitrhsfunction)
5824: {
5825:   PetscFunctionBegin;
5827:   *use_splitrhsfunction = ts->use_splitrhsfunction;
5828:   PetscFunctionReturn(PETSC_SUCCESS);
5829: }

5831: /*@
5832:   TSSetMatStructure - sets the relationship between the nonzero structure of the RHS Jacobian matrix to the IJacobian matrix.

5834:   Logically  Collective

5836:   Input Parameters:
5837: + ts  - the time-stepper
5838: - str - the structure (the default is `UNKNOWN_NONZERO_PATTERN`)

5840:   Level: intermediate

5842:   Note:
5843:   When the relationship between the nonzero structures is known and supplied the solution process can be much faster

5845: .seealso: [](ch_ts), `TS`, `MatAXPY()`, `MatStructure`
5846:  @*/
5847: PetscErrorCode TSSetMatStructure(TS ts, MatStructure str)
5848: {
5849:   PetscFunctionBegin;
5851:   ts->axpy_pattern = str;
5852:   PetscFunctionReturn(PETSC_SUCCESS);
5853: }

5855: /*@
5856:   TSSetEvaluationTimes - sets the evaluation points. The solution will be computed and stored for each time requested

5858:   Collective

5860:   Input Parameters:
5861: + ts          - the time-stepper
5862: . n           - number of the time points
5863: - time_points - array of the time points

5865:   Options Database Key:
5866: . -ts_eval_times <t0,...tn> - Sets the evaluation times

5868:   Level: intermediate

5870:   Notes:
5871:   The elements in `time_points` must be all increasing. They correspond to the intermediate points for time integration.

5873:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

5875:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using evaluation times may
5876:   pressure the memory system when using a large number of time points.

5878: .seealso: [](ch_ts), `TS`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`, `TSSetTimeSpan()`
5879:  @*/
5880: PetscErrorCode TSSetEvaluationTimes(TS ts, PetscInt n, PetscReal *time_points)
5881: {
5882:   PetscBool is_sorted;

5884:   PetscFunctionBegin;
5886:   if (ts->eval_times && n != ts->eval_times->num_time_points) {
5887:     PetscCall(PetscFree(ts->eval_times->time_points));
5888:     PetscCall(VecDestroyVecs(ts->eval_times->num_time_points, &ts->eval_times->sol_vecs));
5889:     PetscCall(PetscMalloc1(n, &ts->eval_times->time_points));
5890:   }
5891:   if (!ts->eval_times) {
5892:     TSEvaluationTimes eval_times;
5893:     PetscCall(PetscNew(&eval_times));
5894:     PetscCall(PetscMalloc1(n, &eval_times->time_points));
5895:     eval_times->reltol  = 1e-6;
5896:     eval_times->abstol  = 10 * PETSC_MACHINE_EPSILON;
5897:     eval_times->worktol = 0;
5898:     ts->eval_times      = eval_times;
5899:   }
5900:   ts->eval_times->num_time_points = n;
5901:   PetscCall(PetscSortedReal(n, time_points, &is_sorted));
5902:   PetscCheck(is_sorted, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "time_points array must be sorted");
5903:   PetscCall(PetscArraycpy(ts->eval_times->time_points, time_points, n));
5904:   PetscFunctionReturn(PETSC_SUCCESS);
5905: }

5907: /*@C
5908:   TSGetEvaluationTimes - gets the evaluation times set with `TSSetEvaluationTimes()`

5910:   Not Collective

5912:   Input Parameter:
5913: . ts - the time-stepper

5915:   Output Parameters:
5916: + n           - number of the time points
5917: - time_points - array of the time points

5919:   Level: beginner

5921:   Note:
5922:   The values obtained are valid until the `TS` object is destroyed.

5924:   Both `n` and `time_points` can be `NULL`.

5926:   Also used to see time points set by `TSSetTimeSpan()`.

5928: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationSolutions()`
5929:  @*/
5930: PetscErrorCode TSGetEvaluationTimes(TS ts, PetscInt *n, const PetscReal *time_points[])
5931: {
5932:   PetscFunctionBegin;
5934:   if (n) PetscAssertPointer(n, 2);
5935:   if (time_points) PetscAssertPointer(time_points, 3);
5936:   if (!ts->eval_times) {
5937:     if (n) *n = 0;
5938:     if (time_points) *time_points = NULL;
5939:   } else {
5940:     if (n) *n = ts->eval_times->num_time_points;
5941:     if (time_points) *time_points = ts->eval_times->time_points;
5942:   }
5943:   PetscFunctionReturn(PETSC_SUCCESS);
5944: }

5946: /*@C
5947:   TSGetEvaluationSolutions - Get the number of solutions and the solutions at the evaluation time points specified

5949:   Input Parameter:
5950: . ts - the `TS` context obtained from `TSCreate()`

5952:   Output Parameters:
5953: + nsol      - the number of solutions
5954: . sol_times - array of solution times corresponding to the solution vectors. See note below
5955: - Sols      - the solution vectors

5957:   Level: intermediate

5959:   Notes:
5960:   Both `nsol` and `Sols` can be `NULL`.

5962:   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()`.
5963:   For example, manipulating the step size, especially with a reduced precision, may cause `TS` to step over certain evaluation times.

5965:   Also used to see view solutions requested by `TSSetTimeSpan()`.

5967: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`
5968: @*/
5969: PetscErrorCode TSGetEvaluationSolutions(TS ts, PetscInt *nsol, const PetscReal *sol_times[], Vec **Sols)
5970: {
5971:   PetscFunctionBegin;
5973:   if (nsol) PetscAssertPointer(nsol, 2);
5974:   if (sol_times) PetscAssertPointer(sol_times, 3);
5975:   if (Sols) PetscAssertPointer(Sols, 4);
5976:   if (!ts->eval_times) {
5977:     if (nsol) *nsol = 0;
5978:     if (sol_times) *sol_times = NULL;
5979:     if (Sols) *Sols = NULL;
5980:   } else {
5981:     if (nsol) *nsol = ts->eval_times->sol_ctr;
5982:     if (sol_times) *sol_times = ts->eval_times->sol_times;
5983:     if (Sols) *Sols = ts->eval_times->sol_vecs;
5984:   }
5985:   PetscFunctionReturn(PETSC_SUCCESS);
5986: }

5988: /*@
5989:   TSSetTimeSpan - sets the time span. The solution will be computed and stored for each time requested in the span

5991:   Collective

5993:   Input Parameters:
5994: + ts         - the time-stepper
5995: . n          - number of the time points (>=2)
5996: - span_times - array of the time points. The first element and the last element are the initial time and the final time respectively.

5998:   Options Database Key:
5999: . -ts_time_span <t0,...tf> - Sets the time span

6001:   Level: intermediate

6003:   Notes:
6004:   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.

6006:   The elements in tspan must be all increasing. They correspond to the intermediate points for time integration.

6008:   `TS_EXACTFINALTIME_MATCHSTEP` must be used to make the last time step in each sub-interval match the intermediate points specified.

6010:   The intermediate solutions are saved in a vector array that can be accessed with `TSGetEvaluationSolutions()`. Thus using time span may
6011:   pressure the memory system when using a large number of span points.

6013: .seealso: [](ch_ts), `TS`, `TSSetEvaluationTimes()`, `TSGetEvaluationTimes()`, `TSGetEvaluationSolutions()`
6014:  @*/
6015: PetscErrorCode TSSetTimeSpan(TS ts, PetscInt n, PetscReal *span_times)
6016: {
6017:   PetscFunctionBegin;
6019:   PetscCheck(n >= 2, PetscObjectComm((PetscObject)ts), PETSC_ERR_ARG_WRONG, "Minimum time span size is 2 but %" PetscInt_FMT " is provided", n);
6020:   PetscCall(TSSetEvaluationTimes(ts, n, span_times));
6021:   PetscCall(TSSetTime(ts, span_times[0]));
6022:   PetscCall(TSSetMaxTime(ts, span_times[n - 1]));
6023:   PetscFunctionReturn(PETSC_SUCCESS);
6024: }

6026: /*@
6027:   TSPruneIJacobianColor - Remove nondiagonal zeros in the Jacobian matrix and update the `MatMFFD` coloring information.

6029:   Collective

6031:   Input Parameters:
6032: + ts - the `TS` context
6033: . J  - Jacobian matrix (not altered in this routine)
6034: - B  - newly computed Jacobian matrix to use with preconditioner

6036:   Level: intermediate

6038:   Notes:
6039:   This function improves the `MatFDColoring` performance when the Jacobian matrix was over-allocated or contains
6040:   many constant zeros entries, which is typically the case when the matrix is generated by a `DM`
6041:   and multiple fields are involved.

6043:   Users need to make sure that the Jacobian matrix is properly filled to reflect the sparsity
6044:   structure. For `MatFDColoring`, the values of nonzero entries are not important. So one can
6045:   usually call `TSComputeIJacobian()` with randomized input vectors to generate a dummy Jacobian.
6046:   `TSComputeIJacobian()` should be called before `TSSolve()` but after `TSSetUp()`.

6048: .seealso: [](ch_ts), `TS`, `MatFDColoring`, `TSComputeIJacobianDefaultColor()`, `MatEliminateZeros()`, `MatFDColoringCreate()`, `MatFDColoringSetFunction()`
6049: @*/
6050: PetscErrorCode TSPruneIJacobianColor(TS ts, Mat J, Mat B)
6051: {
6052:   MatColoring   mc            = NULL;
6053:   ISColoring    iscoloring    = NULL;
6054:   MatFDColoring matfdcoloring = NULL;

6056:   PetscFunctionBegin;
6057:   /* Generate new coloring after eliminating zeros in the matrix */
6058:   PetscCall(MatEliminateZeros(B, PETSC_TRUE));
6059:   PetscCall(MatColoringCreate(B, &mc));
6060:   PetscCall(MatColoringSetDistance(mc, 2));
6061:   PetscCall(MatColoringSetType(mc, MATCOLORINGSL));
6062:   PetscCall(MatColoringSetFromOptions(mc));
6063:   PetscCall(MatColoringApply(mc, &iscoloring));
6064:   PetscCall(MatColoringDestroy(&mc));
6065:   /* Replace the old coloring with the new one */
6066:   PetscCall(MatFDColoringCreate(B, iscoloring, &matfdcoloring));
6067:   PetscCall(MatFDColoringSetFunction(matfdcoloring, (PetscErrorCode (*)(void))SNESTSFormFunction, (void *)ts));
6068:   PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
6069:   PetscCall(MatFDColoringSetUp(B, iscoloring, matfdcoloring));
6070:   PetscCall(PetscObjectCompose((PetscObject)B, "TSMatFDColoring", (PetscObject)matfdcoloring));
6071:   PetscCall(PetscObjectDereference((PetscObject)matfdcoloring));
6072:   PetscCall(ISColoringDestroy(&iscoloring));
6073:   PetscFunctionReturn(PETSC_SUCCESS);
6074: }