PetscErrorCode TSEventHandler(TS ts)
{
PetscErrorCode ierr;
TSEvent event;
PetscReal t;
Vec U;
PetscInt i;
PetscReal dt,dt_min;
PetscInt rollback=0,in[2],out[2];
PetscInt fvalue_sign,fvalueprev_sign;
PetscFunctionBegin;
PetscValidHeaderSpecific(ts,TS_CLASSID,1);
if (!ts->event) PetscFunctionReturn(0);
event = ts->event;
ierr = TSGetTime(ts,&t);CHKERRQ(ierr);
ierr = TSGetTimeStep(ts,&dt);CHKERRQ(ierr);
ierr = TSGetSolution(ts,&U);CHKERRQ(ierr);
if (event->status == TSEVENT_NONE) {
if (ts->steps == 1) /* After first successful step */
event->timestep_orig = ts->ptime - ts->ptime_prev;
event->timestep_prev = dt;
}
if (event->status == TSEVENT_RESET_NEXTSTEP) {
/* Restore time step */
dt = PetscMin(event->timestep_orig,event->timestep_prev);
ierr = TSSetTimeStep(ts,dt);CHKERRQ(ierr);
event->status = TSEVENT_NONE;
}
if (event->status == TSEVENT_NONE) {
event->ptime_end = t;
}
ierr = VecLockPush(U);CHKERRQ(ierr);
ierr = (*event->eventhandler)(ts,t,U,event->fvalue,event->ctx);CHKERRQ(ierr);
ierr = VecLockPop(U);CHKERRQ(ierr);
for (i=0; i < event->nevents; i++) {
if (PetscAbsScalar(event->fvalue[i]) < event->vtol[i]) {
event->status = TSEVENT_ZERO;
event->fvalue_right[i] = event->fvalue[i];
continue;
}
fvalue_sign = PetscSign(PetscRealPart(event->fvalue[i]));
fvalueprev_sign = PetscSign(PetscRealPart(event->fvalue_prev[i]));
if (fvalueprev_sign != 0 && (fvalue_sign != fvalueprev_sign) && (PetscAbsScalar(event->fvalue_prev[i]) > event->vtol[i])) {
switch (event->direction[i]) {
case -1:
if (fvalue_sign < 0) {
rollback = 1;
/* Compute new time step */
dt = TSEventComputeStepSize(event->ptime_prev,t,event->ptime_right,event->fvalue_prev[i],event->fvalue[i],event->fvalue_right[i],event->side[i],dt);
if (event->monitor) {
ierr = PetscViewerASCIIPrintf(event->monitor,"TSEvent: iter %D - Event %D interval detected [%g - %g]\n",event->iterctr,i,(double)event->ptime_prev,(double)t);CHKERRQ(ierr);
}
event->fvalue_right[i] = event->fvalue[i];
event->side[i] = 1;
if (!event->iterctr) event->zerocrossing[i] = PETSC_TRUE;
event->status = TSEVENT_LOCATED_INTERVAL;
}
break;
case 1:
if (fvalue_sign > 0) {
rollback = 1;
/* Compute new time step */
dt = TSEventComputeStepSize(event->ptime_prev,t,event->ptime_right,event->fvalue_prev[i],event->fvalue[i],event->fvalue_right[i],event->side[i],dt);
if (event->monitor) {
ierr = PetscViewerASCIIPrintf(event->monitor,"TSEvent: iter %D - Event %D interval detected [%g - %g]\n",event->iterctr,i,(double)event->ptime_prev,(double)t);CHKERRQ(ierr);
}
event->fvalue_right[i] = event->fvalue[i];
event->side[i] = 1;
if (!event->iterctr) event->zerocrossing[i] = PETSC_TRUE;
event->status = TSEVENT_LOCATED_INTERVAL;
}
break;
case 0:
rollback = 1;
/* Compute new time step */
dt = TSEventComputeStepSize(event->ptime_prev,t,event->ptime_right,event->fvalue_prev[i],event->fvalue[i],event->fvalue_right[i],event->side[i],dt);
if (event->monitor) {
ierr = PetscViewerASCIIPrintf(event->monitor,"TSEvent: iter %D - Event %D interval detected [%g - %g]\n",event->iterctr,i,(double)event->ptime_prev,(double)t);CHKERRQ(ierr);
}
event->fvalue_right[i] = event->fvalue[i];
event->side[i] = 1;
if (!event->iterctr) event->zerocrossing[i] = PETSC_TRUE;
event->status = TSEVENT_LOCATED_INTERVAL;
break;
}
}
}
in[0] = event->status; in[1] = rollback;
ierr = MPIU_Allreduce(in,out,2,MPIU_INT,MPI_MAX,PetscObjectComm((PetscObject)ts));CHKERRQ(ierr);
event->status = (TSEventStatus)out[0]; rollback = out[1];
if (rollback) event->status = TSEVENT_LOCATED_INTERVAL;
event->nevents_zero = 0;
if (event->status == TSEVENT_ZERO) {
for (i=0; i < event->nevents; i++) {
if (PetscAbsScalar(event->fvalue[i]) < event->vtol[i]) {
event->events_zero[event->nevents_zero++] = i;
if (event->monitor) {
ierr = PetscViewerASCIIPrintf(event->monitor,"TSEvent: Event %D zero crossing at time %g located in %D iterations\n",i,(double)t,event->iterctr);CHKERRQ(ierr);
}
event->zerocrossing[i] = PETSC_FALSE;
}
event->side[i] = 0;
}
ierr = TSPostEvent(ts,t,U);CHKERRQ(ierr);
dt = event->ptime_end - t;
if (PetscAbsReal(dt) < PETSC_SMALL) { /* we hit the event, continue with the candidate time step */
dt = event->timestep_prev;
event->status = TSEVENT_NONE;
}
ierr = TSSetTimeStep(ts,dt);CHKERRQ(ierr);
event->iterctr = 0;
PetscFunctionReturn(0);
}
if (event->status == TSEVENT_LOCATED_INTERVAL) {
ierr = TSRollBack(ts);CHKERRQ(ierr);
ierr = TSSetConvergedReason(ts,TS_CONVERGED_ITERATING);CHKERRQ(ierr);
event->status = TSEVENT_PROCESSING;
event->ptime_right = t;
} else {
for (i=0; i < event->nevents; i++) {
if (event->status == TSEVENT_PROCESSING && event->zerocrossing[i]) {
/* Compute new time step */
dt = TSEventComputeStepSize(event->ptime_prev,t,event->ptime_right,event->fvalue_prev[i],event->fvalue[i],event->fvalue_right[i],event->side[i],dt);
event->side[i] = -1;
}
event->fvalue_prev[i] = event->fvalue[i];
}
if (event->monitor && event->status == TSEVENT_PROCESSING) {
ierr = PetscViewerASCIIPrintf(event->monitor,"TSEvent: iter %D - Stepping forward as no event detected in interval [%g - %g]\n",event->iterctr,(double)event->ptime_prev,(double)t);CHKERRQ(ierr);
}
event->ptime_prev = t;
}
if (event->status == TSEVENT_PROCESSING) event->iterctr++;
ierr = MPIU_Allreduce(&dt,&dt_min,1,MPIU_REAL,MPIU_MIN,PetscObjectComm((PetscObject)ts));CHKERRQ(ierr);
ierr = TSSetTimeStep(ts,dt_min);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
static PetscErrorCode TSStep_Theta(TS ts)
{
TS_Theta *th = (TS_Theta*)ts->data;
PetscInt its,lits,reject,next_scheme;
PetscReal next_time_step;
TSAdapt adapt;
PetscBool stageok,accept = PETSC_TRUE;
PetscErrorCode ierr;
PetscFunctionBegin;
th->status = TS_STEP_INCOMPLETE;
ierr = VecCopy(ts->vec_sol,th->X0);CHKERRQ(ierr);
for (reject=0; !ts->reason && th->status != TS_STEP_COMPLETE; ts->reject++) {
PetscReal shift = 1./(th->Theta*ts->time_step);
th->stage_time = ts->ptime + (th->endpoint ? 1. : th->Theta)*ts->time_step;
ierr = TSPreStep(ts);CHKERRQ(ierr);
ierr = TSPreStage(ts,th->stage_time);CHKERRQ(ierr);
if (th->endpoint) { /* This formulation assumes linear time-independent mass matrix */
ierr = VecZeroEntries(th->Xdot);CHKERRQ(ierr);
if (!th->affine) {ierr = VecDuplicate(ts->vec_sol,&th->affine);CHKERRQ(ierr);}
ierr = TSComputeIFunction(ts,ts->ptime,ts->vec_sol,th->Xdot,th->affine,PETSC_FALSE);CHKERRQ(ierr);
ierr = VecScale(th->affine,(th->Theta-1.)/th->Theta);CHKERRQ(ierr);
}
if (th->extrapolate) {
ierr = VecWAXPY(th->X,1./shift,th->Xdot,ts->vec_sol);CHKERRQ(ierr);
} else {
ierr = VecCopy(ts->vec_sol,th->X);CHKERRQ(ierr);
}
ierr = SNESSolve(ts->snes,th->affine,th->X);CHKERRQ(ierr);
ierr = SNESGetIterationNumber(ts->snes,&its);CHKERRQ(ierr);
ierr = SNESGetLinearSolveIterations(ts->snes,&lits);CHKERRQ(ierr);
ts->snes_its += its; ts->ksp_its += lits;
ierr = TSPostStage(ts,th->stage_time,0,&(th->X));CHKERRQ(ierr);
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptCheckStage(adapt,ts,&stageok);CHKERRQ(ierr);
if (!stageok) {accept = PETSC_FALSE; goto reject_step;}
ierr = TSEvaluateStep(ts,th->order,ts->vec_sol,NULL);CHKERRQ(ierr);
th->status = TS_STEP_PENDING;
/* Register only the current method as a candidate because we're not supporting multiple candidates yet. */
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptCandidatesClear(adapt);CHKERRQ(ierr);
ierr = TSAdaptCandidateAdd(adapt,NULL,th->order,1,th->ccfl,1.0,PETSC_TRUE);CHKERRQ(ierr);
ierr = TSAdaptChoose(adapt,ts,ts->time_step,&next_scheme,&next_time_step,&accept);CHKERRQ(ierr);
if (!accept) { /* Roll back the current step */
ts->ptime += next_time_step; /* This will be undone in rollback */
th->status = TS_STEP_INCOMPLETE;
ierr = TSRollBack(ts);CHKERRQ(ierr);
goto reject_step;
}
/* ignore next_scheme for now */
ts->ptime += ts->time_step;
ts->time_step = next_time_step;
ts->steps++;
th->status = TS_STEP_COMPLETE;
break;
reject_step:
if (!ts->reason && ++reject > ts->max_reject && ts->max_reject >= 0) {
ts->reason = TS_DIVERGED_STEP_REJECTED;
ierr = PetscInfo2(ts,"Step=%D, step rejections %D greater than current TS allowed, stopping solve\n",ts->steps,reject);CHKERRQ(ierr);
}
continue;
}
PetscFunctionReturn(0);
}
