static PetscErrorCode TSSetUp_Theta(TS ts)
{
TS_Theta *th = (TS_Theta*)ts->data;
PetscErrorCode ierr;
SNES snes;
TSAdapt adapt;
DM dm;
PetscFunctionBegin;
ierr = VecDuplicate(ts->vec_sol,&th->X);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->Xdot);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->X0);CHKERRQ(ierr);
ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
if (dm) {
ierr = DMCoarsenHookAdd(dm,DMCoarsenHook_TSTheta,DMRestrictHook_TSTheta,ts);CHKERRQ(ierr);
ierr = DMSubDomainHookAdd(dm,DMSubDomainHook_TSTheta,DMSubDomainRestrictHook_TSTheta,ts);CHKERRQ(ierr);
}
if (th->Theta == 0.5 && th->endpoint) th->order = 2;
else th->order = 1;
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
if (!th->adapt) {
ierr = TSAdaptSetType(adapt,TSADAPTNONE);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
static PetscErrorCode TSSetUp_Alpha(TS ts)
{
TS_Alpha *th = (TS_Alpha*)ts->data;
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = VecDuplicate(ts->vec_sol,&th->X0);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->Xa);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->X1);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->V0);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->Va);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->V1);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->A0);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->Aa);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->A1);CHKERRQ(ierr);
ierr = TSGetAdapt(ts,&ts->adapt);CHKERRQ(ierr);
ierr = TSAdaptCandidatesClear(ts->adapt);CHKERRQ(ierr);
if (!th->adapt) {
ierr = TSAdaptSetType(ts->adapt,TSADAPTNONE);CHKERRQ(ierr);
} else {
ierr = VecDuplicate(ts->vec_sol,&th->vec_sol_prev);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->vec_dot_prev);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->vec_lte_work[0]);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->vec_lte_work[1]);CHKERRQ(ierr);
if (ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED)
ts->exact_final_time = TS_EXACTFINALTIME_MATCHSTEP;
}
ierr = TSGetSNES(ts,&ts->snes);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*
TSAdaptSetFromOptions - Sets various TSAdapt parameters from user options.
Collective on TSAdapt
Input Parameter:
. adapt - the TSAdapt context
Options Database Keys:
. -ts_adapt_type <type> - basic
Level: advanced
Notes:
This function is automatically called by TSSetFromOptions()
.keywords: TS, TSGetAdapt(), TSAdaptSetType()
.seealso: TSGetType()
*/
PetscErrorCode TSAdaptSetFromOptions(PetscOptionItems *PetscOptionsObject,TSAdapt adapt)
{
PetscErrorCode ierr;
char type[256] = TSADAPTBASIC;
PetscBool set,flg;
PetscFunctionBegin;
PetscValidHeaderSpecific(adapt,TSADAPT_CLASSID,1);
/* This should use PetscOptionsBegin() if/when this becomes an object used outside of TS, but currently this
* function can only be called from inside TSSetFromOptions() */
ierr = PetscOptionsHead(PetscOptionsObject,"TS Adaptivity options");CHKERRQ(ierr);
ierr = PetscOptionsFList("-ts_adapt_type","Algorithm to use for adaptivity","TSAdaptSetType",TSAdaptList,
((PetscObject)adapt)->type_name ? ((PetscObject)adapt)->type_name : type,type,sizeof(type),&flg);CHKERRQ(ierr);
if (flg || !((PetscObject)adapt)->type_name) {
ierr = TSAdaptSetType(adapt,type);CHKERRQ(ierr);
}
ierr = PetscOptionsReal("-ts_adapt_dt_min","Minimum time step considered","TSAdaptSetStepLimits",adapt->dt_min,&adapt->dt_min,NULL);CHKERRQ(ierr);
ierr = PetscOptionsReal("-ts_adapt_dt_max","Maximum time step considered","TSAdaptSetStepLimits",adapt->dt_max,&adapt->dt_max,NULL);CHKERRQ(ierr);
ierr = PetscOptionsReal("-ts_adapt_scale_solve_failed","Scale step by this factor if solve fails","",adapt->scale_solve_failed,&adapt->scale_solve_failed,NULL);CHKERRQ(ierr);
ierr = PetscOptionsBool("-ts_adapt_monitor","Print choices made by adaptive controller","TSAdaptSetMonitor",adapt->monitor ? PETSC_TRUE : PETSC_FALSE,&flg,&set);CHKERRQ(ierr);
ierr = PetscOptionsEnum("-ts_adapt_wnormtype","Type of norm computed for error estimation","",NormTypes,(PetscEnum)adapt->wnormtype,(PetscEnum*)&adapt->wnormtype,NULL);CHKERRQ(ierr);
if (adapt->wnormtype != NORM_2 && adapt->wnormtype != NORM_INFINITY) SETERRQ(PetscObjectComm((PetscObject)adapt),PETSC_ERR_SUP,"Only 2-norm and infinite norm supported");
if (set) {ierr = TSAdaptSetMonitor(adapt,flg);CHKERRQ(ierr);}
if (adapt->ops->setfromoptions) {ierr = (*adapt->ops->setfromoptions)(PetscOptionsObject,adapt);CHKERRQ(ierr);}
ierr = PetscOptionsTail();CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*
TSAdaptSetFromOptions - Sets various TSAdapt parameters from user options.
Collective on TSAdapt
Input Parameter:
. adapt - the TSAdapt context
Options Database Keys:
+ -ts_adapt_type <type> - algorithm to use for adaptivity
. -ts_adapt_always_accept - always accept steps regardless of error/stability goals
. -ts_adapt_safety <safety> - safety factor relative to target error/stability goal
. -ts_adapt_reject_safety <safety> - extra safety factor to apply if the last step was rejected
. -ts_adapt_clip <low,high> - admissible time step decrease and increase factors
. -ts_adapt_dt_min <min> - minimum timestep to use
. -ts_adapt_dt_max <max> - maximum timestep to use
. -ts_adapt_scale_solve_failed <scale> - scale timestep by this factor if a solve fails
. -ts_adapt_wnormtype <2 or infinity> - type of norm for computing error estimates
- -ts_adapt_time_step_increase_delay - number of timesteps to delay increasing the time step after it has been decreased due to failed solver
Level: advanced
Notes:
This function is automatically called by TSSetFromOptions()
.keywords: TS, TSGetAdapt(), TSAdaptSetType(), TSAdaptSetStepLimits()
.seealso: TSGetAdapt(), TSAdaptSetType(), TSAdaptSetAlwaysAccept(), TSAdaptSetSafety(),
TSAdaptSetClip(), TSAdaptSetStepLimits(), TSAdaptSetMonitor()
*/
PetscErrorCode TSAdaptSetFromOptions(PetscOptionItems *PetscOptionsObject,TSAdapt adapt)
{
PetscErrorCode ierr;
char type[256] = TSADAPTBASIC;
PetscReal safety,reject_safety,clip[2],hmin,hmax;
PetscBool set,flg;
PetscInt two;
PetscFunctionBegin;
PetscValidHeaderSpecific(adapt,TSADAPT_CLASSID,1);
/* This should use PetscOptionsBegin() if/when this becomes an object used outside of TS, but currently this
* function can only be called from inside TSSetFromOptions() */
ierr = PetscOptionsHead(PetscOptionsObject,"TS Adaptivity options");CHKERRQ(ierr);
ierr = PetscOptionsFList("-ts_adapt_type","Algorithm to use for adaptivity","TSAdaptSetType",TSAdaptList,((PetscObject)adapt)->type_name ? ((PetscObject)adapt)->type_name : type,type,sizeof(type),&flg);CHKERRQ(ierr);
if (flg || !((PetscObject)adapt)->type_name) {
ierr = TSAdaptSetType(adapt,type);CHKERRQ(ierr);
}
ierr = PetscOptionsBool("-ts_adapt_always_accept","Always accept the step","TSAdaptSetAlwaysAccept",adapt->always_accept,&flg,&set);CHKERRQ(ierr);
if (set) {ierr = TSAdaptSetAlwaysAccept(adapt,flg);CHKERRQ(ierr);}
safety = adapt->safety; reject_safety = adapt->reject_safety;
ierr = PetscOptionsReal("-ts_adapt_safety","Safety factor relative to target error/stability goal","TSAdaptSetSafety",safety,&safety,&set);CHKERRQ(ierr);
ierr = PetscOptionsReal("-ts_adapt_reject_safety","Extra safety factor to apply if the last step was rejected","TSAdaptSetSafety",reject_safety,&reject_safety,&flg);CHKERRQ(ierr);
if (set || flg) {ierr = TSAdaptSetSafety(adapt,safety,reject_safety);CHKERRQ(ierr);}
two = 2; clip[0] = adapt->clip[0]; clip[1] = adapt->clip[1];
ierr = PetscOptionsRealArray("-ts_adapt_clip","Admissible decrease/increase factor in step size","TSAdaptSetClip",clip,&two,&set);CHKERRQ(ierr);
if (set && (two != 2)) SETERRQ(PetscObjectComm((PetscObject)adapt),PETSC_ERR_ARG_OUTOFRANGE,"Must give exactly two values to -ts_adapt_clip");
if (set) {ierr = TSAdaptSetClip(adapt,clip[0],clip[1]);CHKERRQ(ierr);}
hmin = adapt->dt_min; hmax = adapt->dt_max;
ierr = PetscOptionsReal("-ts_adapt_dt_min","Minimum time step considered","TSAdaptSetStepLimits",hmin,&hmin,&set);CHKERRQ(ierr);
ierr = PetscOptionsReal("-ts_adapt_dt_max","Maximum time step considered","TSAdaptSetStepLimits",hmax,&hmax,&flg);CHKERRQ(ierr);
if (set || flg) {ierr = TSAdaptSetStepLimits(adapt,hmin,hmax);CHKERRQ(ierr);}
ierr = PetscOptionsReal("-ts_adapt_max_ignore","Adaptor ignores (absolute) solution values smaller than this value","",adapt->ignore_max,&adapt->ignore_max,&set);CHKERRQ(ierr);
ierr = PetscOptionsBool("-ts_adapt_glee_use_local","GLEE adaptor uses local error estimation for step control","",adapt->glee_use_local,&adapt->glee_use_local,&set);CHKERRQ(ierr);
ierr = PetscOptionsReal("-ts_adapt_scale_solve_failed","Scale step by this factor if solve fails","",adapt->scale_solve_failed,&adapt->scale_solve_failed,NULL);CHKERRQ(ierr);
ierr = PetscOptionsEnum("-ts_adapt_wnormtype","Type of norm computed for error estimation","",NormTypes,(PetscEnum)adapt->wnormtype,(PetscEnum*)&adapt->wnormtype,NULL);CHKERRQ(ierr);
if (adapt->wnormtype != NORM_2 && adapt->wnormtype != NORM_INFINITY) SETERRQ(PetscObjectComm((PetscObject)adapt),PETSC_ERR_SUP,"Only 2-norm and infinite norm supported");
ierr = PetscOptionsInt("-ts_adapt_time_step_increase_delay","Number of timesteps to delay increasing the time step after it has been decreased due to failed solver","TSAdaptSetTimeStepIncreaseDelay",adapt->timestepjustdecreased_delay,&adapt->timestepjustdecreased_delay,NULL);CHKERRQ(ierr);
ierr = PetscOptionsBool("-ts_adapt_monitor","Print choices made by adaptive controller","TSAdaptSetMonitor",adapt->monitor ? PETSC_TRUE : PETSC_FALSE,&flg,&set);CHKERRQ(ierr);
if (set) {ierr = TSAdaptSetMonitor(adapt,flg);CHKERRQ(ierr);}
if (adapt->ops->setfromoptions) {ierr = (*adapt->ops->setfromoptions)(PetscOptionsObject,adapt);CHKERRQ(ierr);}
ierr = PetscOptionsTail();CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*@C
TSAdaptLoad - Loads a TSAdapt that has been stored in binary with TSAdaptView().
Collective on PetscViewer
Input Parameters:
+ newdm - the newly loaded TSAdapt, this needs to have been created with TSAdaptCreate() or
some related function before a call to TSAdaptLoad().
- viewer - binary file viewer, obtained from PetscViewerBinaryOpen() or
HDF5 file viewer, obtained from PetscViewerHDF5Open()
Level: intermediate
Notes:
The type is determined by the data in the file, any type set into the TSAdapt before this call is ignored.
Notes for advanced users:
Most users should not need to know the details of the binary storage
format, since TSAdaptLoad() and TSAdaptView() completely hide these details.
But for anyone who's interested, the standard binary matrix storage
format is
.vb
has not yet been determined
.ve
.seealso: PetscViewerBinaryOpen(), TSAdaptView(), MatLoad(), VecLoad()
@*/
PetscErrorCode TSAdaptLoad(TSAdapt adapt,PetscViewer viewer)
{
PetscErrorCode ierr;
PetscBool isbinary;
char type[256];
PetscFunctionBegin;
PetscValidHeaderSpecific(adapt,TSADAPT_CLASSID,1);
PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
ierr = PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);CHKERRQ(ierr);
ierr = TSAdaptSetType(adapt,type);CHKERRQ(ierr);
if (adapt->ops->load) {
ierr = (*adapt->ops->load)(adapt,viewer);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
static PetscErrorCode TSSetUp_Theta(TS ts)
{
TS_Theta *th = (TS_Theta*)ts->data;
PetscErrorCode ierr;
PetscFunctionBegin;
if (!th->VecCostIntegral0 && ts->vec_costintegral && ts->costintegralfwd) { /* back up cost integral */
ierr = VecDuplicate(ts->vec_costintegral,&th->VecCostIntegral0);CHKERRQ(ierr);
}
if (!th->X) {
ierr = VecDuplicate(ts->vec_sol,&th->X);CHKERRQ(ierr);
}
if (!th->Xdot) {
ierr = VecDuplicate(ts->vec_sol,&th->Xdot);CHKERRQ(ierr);
}
if (!th->X0) {
ierr = VecDuplicate(ts->vec_sol,&th->X0);CHKERRQ(ierr);
}
if (th->endpoint) {
ierr = VecDuplicate(ts->vec_sol,&th->affine);CHKERRQ(ierr);
}
th->order = (th->Theta == 0.5) ? 2 : 1;
ierr = TSGetDM(ts,&ts->dm);CHKERRQ(ierr);
ierr = DMCoarsenHookAdd(ts->dm,DMCoarsenHook_TSTheta,DMRestrictHook_TSTheta,ts);CHKERRQ(ierr);
ierr = DMSubDomainHookAdd(ts->dm,DMSubDomainHook_TSTheta,DMSubDomainRestrictHook_TSTheta,ts);CHKERRQ(ierr);
ierr = TSGetAdapt(ts,&ts->adapt);CHKERRQ(ierr);
ierr = TSAdaptCandidatesClear(ts->adapt);CHKERRQ(ierr);
if (!th->adapt) {
ierr = TSAdaptSetType(ts->adapt,TSADAPTNONE);CHKERRQ(ierr);
} else {
ierr = VecDuplicate(ts->vec_sol,&th->vec_sol_prev);CHKERRQ(ierr);
ierr = VecDuplicate(ts->vec_sol,&th->vec_lte_work);CHKERRQ(ierr);
if (ts->exact_final_time == TS_EXACTFINALTIME_UNSPECIFIED)
ts->exact_final_time = TS_EXACTFINALTIME_MATCHSTEP;
}
ierr = TSGetSNES(ts,&ts->snes);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*@
TSAdaptCreate - create an adaptive controller context for time stepping
Collective on MPI_Comm
Input Parameter:
. comm - The communicator
Output Parameter:
. adapt - new TSAdapt object
Level: developer
Notes:
TSAdapt creation is handled by TS, so users should not need to call this function.
.keywords: TSAdapt, create
.seealso: TSGetAdapt(), TSAdaptSetType(), TSAdaptDestroy()
@*/
PetscErrorCode TSAdaptCreate(MPI_Comm comm,TSAdapt *inadapt)
{
PetscErrorCode ierr;
TSAdapt adapt;
PetscFunctionBegin;
PetscValidPointer(inadapt,1);
*inadapt = NULL;
ierr = TSAdaptInitializePackage();CHKERRQ(ierr);
ierr = PetscHeaderCreate(adapt,TSADAPT_CLASSID,"TSAdapt","Time stepping adaptivity","TS",comm,TSAdaptDestroy,TSAdaptView);CHKERRQ(ierr);
adapt->dt_min = 1e-20;
adapt->dt_max = 1e50;
adapt->scale_solve_failed = 0.25;
adapt->wnormtype = NORM_2;
ierr = TSAdaptSetType(adapt,TSADAPTBASIC);CHKERRQ(ierr);
*inadapt = adapt;
PetscFunctionReturn(0);
}
int main(int argc,char **argv)
{
TS ts; /* ODE integrator */
Vec U; /* solution will be stored here */
PetscErrorCode ierr;
PetscMPIInt size;
PetscInt n = 2;
PetscScalar *u;
AppCtx app;
PetscInt direction[2];
PetscBool terminate[2];
PetscBool rhs_form=PETSC_FALSE,hist=PETSC_TRUE;
TSAdapt adapt;
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Initialize program
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
if (size > 1) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Only for sequential runs");
app.nbounces = 0;
app.maxbounces = 10;
ierr = PetscOptionsBegin(PETSC_COMM_WORLD,NULL,"ex40 options","");CHKERRQ(ierr);
ierr = PetscOptionsInt("-maxbounces","","",app.maxbounces,&app.maxbounces,NULL);CHKERRQ(ierr);
ierr = PetscOptionsBool("-test_adapthistory","","",hist,&hist,NULL);CHKERRQ(ierr);
ierr = PetscOptionsEnd();CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Create timestepping solver context
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSCreate(PETSC_COMM_WORLD,&ts);CHKERRQ(ierr);
ierr = TSSetType(ts,TSROSW);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Set ODE routines
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSSetProblemType(ts,TS_NONLINEAR);CHKERRQ(ierr);
/* Users are advised against the following branching and code duplication.
For problems without a mass matrix like the one at hand, the RHSFunction
(and companion RHSJacobian) interface is enough to support both explicit
and implicit timesteppers. This tutorial example also deals with the
IFunction/IJacobian interface for demonstration and testing purposes. */
ierr = PetscOptionsGetBool(NULL,NULL,"-rhs-form",&rhs_form,NULL);CHKERRQ(ierr);
if (rhs_form) {
ierr = TSSetRHSFunction(ts,NULL,RHSFunction,NULL);CHKERRQ(ierr);
ierr = TSSetRHSJacobian(ts,NULL,NULL,RHSJacobian,NULL);CHKERRQ(ierr);
} else {
Mat A; /* Jacobian matrix */
ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
ierr = MatSetSizes(A,n,n,PETSC_DETERMINE,PETSC_DETERMINE);CHKERRQ(ierr);
ierr = MatSetType(A,MATDENSE);CHKERRQ(ierr);
ierr = MatSetFromOptions(A);CHKERRQ(ierr);
ierr = MatSetUp(A);CHKERRQ(ierr);
ierr = TSSetIFunction(ts,NULL,IFunction,NULL);CHKERRQ(ierr);
ierr = TSSetIJacobian(ts,A,A,IJacobian,NULL);CHKERRQ(ierr);
ierr = MatDestroy(&A);CHKERRQ(ierr);
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Set initial conditions
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = VecCreate(PETSC_COMM_WORLD,&U);CHKERRQ(ierr);
ierr = VecSetSizes(U,n,PETSC_DETERMINE);CHKERRQ(ierr);
ierr = VecSetUp(U);CHKERRQ(ierr);
ierr = VecGetArray(U,&u);CHKERRQ(ierr);
u[0] = 0.0;
u[1] = 20.0;
ierr = VecRestoreArray(U,&u);CHKERRQ(ierr);
ierr = TSSetSolution(ts,U);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Set solver options
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSSetSaveTrajectory(ts);CHKERRQ(ierr);
ierr = TSSetMaxTime(ts,30.0);CHKERRQ(ierr);
ierr = TSSetExactFinalTime(ts,TS_EXACTFINALTIME_STEPOVER);CHKERRQ(ierr);
ierr = TSSetTimeStep(ts,0.1);CHKERRQ(ierr);
/* The adapative time step controller could take very large timesteps resulting in
the same event occuring multiple times in the same interval. A maximum step size
limit is enforced here to avoid this issue. */
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptSetStepLimits(adapt,0.0,0.5);CHKERRQ(ierr);
/* Set directions and terminate flags for the two events */
direction[0] = -1; direction[1] = -1;
terminate[0] = PETSC_FALSE; terminate[1] = PETSC_TRUE;
ierr = TSSetEventHandler(ts,2,direction,terminate,EventFunction,PostEventFunction,(void*)&app);CHKERRQ(ierr);
ierr = TSSetFromOptions(ts);CHKERRQ(ierr);
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Run timestepping solver
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = TSSolve(ts,U);CHKERRQ(ierr);
if (hist) { /* replay following history */
TSTrajectory tj;
PetscReal tf,t0,dt;
app.nbounces = 0;
ierr = TSGetTime(ts,&tf);CHKERRQ(ierr);
ierr = TSSetMaxTime(ts,tf);CHKERRQ(ierr);
ierr = TSSetStepNumber(ts,0);CHKERRQ(ierr);
ierr = TSRestartStep(ts);CHKERRQ(ierr);
ierr = TSSetExactFinalTime(ts,TS_EXACTFINALTIME_MATCHSTEP);CHKERRQ(ierr);
ierr = TSSetFromOptions(ts);CHKERRQ(ierr);
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptSetType(adapt,TSADAPTHISTORY);CHKERRQ(ierr);
ierr = TSGetTrajectory(ts,&tj);CHKERRQ(ierr);
ierr = TSAdaptHistorySetTrajectory(adapt,tj,PETSC_FALSE);CHKERRQ(ierr);
ierr = TSAdaptHistoryGetStep(adapt,0,&t0,&dt);CHKERRQ(ierr);
/* this example fails with single (or smaller) precision */
#if defined(PETSC_USE_REAL_SINGLE) || defined(PETSC_USE_REAL__FP16)
ierr = TSAdaptSetType(adapt,TSADAPTBASIC);CHKERRQ(ierr);
ierr = TSAdaptSetStepLimits(adapt,0.0,0.5);CHKERRQ(ierr);
ierr = TSSetFromOptions(ts);CHKERRQ(ierr);
#endif
ierr = TSSetTime(ts,t0);CHKERRQ(ierr);
ierr = TSSetTimeStep(ts,dt);CHKERRQ(ierr);
ierr = TSResetTrajectory(ts);CHKERRQ(ierr);
ierr = VecGetArray(U,&u);CHKERRQ(ierr);
u[0] = 0.0;
u[1] = 20.0;
ierr = VecRestoreArray(U,&u);CHKERRQ(ierr);
ierr = TSSolve(ts,U);CHKERRQ(ierr);
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Free work space. All PETSc objects should be destroyed when they are no longer needed.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
ierr = VecDestroy(&U);CHKERRQ(ierr);
ierr = TSDestroy(&ts);CHKERRQ(ierr);
ierr = PetscFinalize();
return ierr;
}