1: #include <petsc/private/tsimpl.h>

  3: const char *const TSConvergedReasons_Shifted[] = {"ADJOINT_DIVERGED_LINEAR_SOLVE", "FORWARD_DIVERGED_LINEAR_SOLVE", "DIVERGED_STEP_REJECTED", "DIVERGED_NONLINEAR_SOLVE", "CONVERGED_ITERATING", "CONVERGED_TIME", "CONVERGED_ITS", "CONVERGED_USER", "CONVERGED_EVENT", "CONVERGED_PSEUDO_FATOL", "CONVERGED_PSEUDO_FATOL", "TSConvergedReason", "TS_", NULL};
  4: const char *const *TSConvergedReasons = TSConvergedReasons_Shifted + 4;

  6: /*@
  7:   TSCreate - This function creates an empty timestepper. The problem type can then be set with `TSSetProblemType()` and the
  8:   type of solver can then be set with `TSSetType()`.

 10:   Collective

 12:   Input Parameter:
 13: . comm - The communicator

 15:   Output Parameter:
 16: . ts - The `TS`

 18:   Level: beginner

 20:   Developer Notes:
 21:   `TS` essentially always creates a `SNES` object even though explicit methods do not use it. This is
 22:   unfortunate and should be fixed at some point. The flag snes->usessnes indicates if the
 23:   particular method does use SNES and regulates if the information about the `SNES` is printed
 24:   in `TSView()`. `TSSetFromOptions(`) does call `SNESSetFromOptions()` which can lead to users being confused
 25:   by help messages about meaningless `SNES` options.

 27: .seealso: [](ch_ts), `TS`, `SNES`, `TSSetType()`, `TSSetUp()`, `TSDestroy()`, `TSSetProblemType()`
 28: @*/
 29: PetscErrorCode TSCreate(MPI_Comm comm, TS *ts)
 30: {
 31:   TS t;

 33:   PetscFunctionBegin;
 34:   PetscAssertPointer(ts, 2);
 35:   PetscCall(TSInitializePackage());

 37:   PetscCall(PetscHeaderCreate(t, TS_CLASSID, "TS", "Time stepping", "TS", comm, TSDestroy, TSView));

 39:   /* General TS description */
 40:   t->problem_type  = TS_NONLINEAR;
 41:   t->equation_type = TS_EQ_UNSPECIFIED;

 43:   t->ptime            = 0.0;
 44:   t->time_step        = 0.1;
 45:   t->max_time         = PETSC_MAX_REAL;
 46:   t->exact_final_time = TS_EXACTFINALTIME_UNSPECIFIED;
 47:   t->steps            = 0;
 48:   t->max_steps        = PETSC_INT_MAX;
 49:   t->steprestart      = PETSC_TRUE;

 51:   t->max_snes_failures = 1;
 52:   t->max_reject        = 10;
 53:   t->errorifstepfailed = PETSC_TRUE;

 55:   t->rhsjacobian.time  = PETSC_MIN_REAL;
 56:   t->rhsjacobian.scale = 1.0;
 57:   t->ijacobian.shift   = 1.0;

 59:   /* All methods that do adaptivity should specify
 60:    * its preferred adapt type in their constructor */
 61:   t->default_adapt_type = TSADAPTNONE;
 62:   t->atol               = 1e-4;
 63:   t->rtol               = 1e-4;
 64:   t->cfltime            = PETSC_MAX_REAL;
 65:   t->cfltime_local      = PETSC_MAX_REAL;

 67:   t->num_rhs_splits = 0;

 69:   t->axpy_pattern = UNKNOWN_NONZERO_PATTERN;
 70:   *ts             = t;
 71:   PetscFunctionReturn(PETSC_SUCCESS);
 72: }