static PetscErrorCode TSAdaptChoose_Basic(TSAdapt adapt,TS ts,PetscReal h,PetscInt *next_sc,PetscReal *next_h,PetscBool *accept,PetscReal *wlte)
{
TSAdapt_Basic *basic = (TSAdapt_Basic*)adapt->data;
PetscErrorCode ierr;
Vec X,Y;
PetscReal enorm,hfac_lte,h_lte,safety;
PetscInt order,stepno;
PetscFunctionBegin;
ierr = TSGetTimeStepNumber(ts,&stepno);CHKERRQ(ierr);
ierr = TSGetSolution(ts,&X);CHKERRQ(ierr);
if (!basic->Y) {ierr = VecDuplicate(X,&basic->Y);CHKERRQ(ierr);}
Y = basic->Y;
order = adapt->candidates.order[0];
ierr = TSEvaluateStep(ts,order-1,Y,NULL);CHKERRQ(ierr);
safety = basic->safety;
ierr = TSErrorNormWRMS(ts,Y,&enorm);CHKERRQ(ierr);
if (enorm > 1.) {
if (!*accept) safety *= basic->reject_safety; /* The last attempt also failed, shorten more aggressively */
if (h < (1 + PETSC_SQRT_MACHINE_EPSILON)*adapt->dt_min) {
ierr = PetscInfo2(adapt,"Estimated scaled local truncation error %g, accepting because step size %g is at minimum\n",(double)enorm,(double)h);CHKERRQ(ierr);
*accept = PETSC_TRUE;
} else if (basic->always_accept) {
ierr = PetscInfo2(adapt,"Estimated scaled local truncation error %g, accepting step of size %g because always_accept is set\n",(double)enorm,(double)h);CHKERRQ(ierr);
*accept = PETSC_TRUE;
} else {
ierr = PetscInfo2(adapt,"Estimated scaled local truncation error %g, rejecting step of size %g\n",(double)enorm,(double)h);CHKERRQ(ierr);
*accept = PETSC_FALSE;
}
} else {
ierr = PetscInfo2(adapt,"Estimated scaled local truncation error %g, accepting step of size %g\n",(double)enorm,(double)h);CHKERRQ(ierr);
*accept = PETSC_TRUE;
}
/* The optimal new step based purely on local truncation error for this step. */
hfac_lte = safety * PetscRealPart(PetscPowScalar((PetscScalar)enorm,(PetscReal)(-1./order)));
h_lte = h * PetscClipInterval(hfac_lte,basic->clip[0],basic->clip[1]);
*next_sc = 0;
*next_h = PetscClipInterval(h_lte,adapt->dt_min,adapt->dt_max);
*wlte = enorm;
PetscFunctionReturn(0);
}
void PETSC_STDCALL tserrornormwrms_(TS ts,Vec Y,PetscReal *norm, int *__ierr ){
*__ierr = TSErrorNormWRMS(
(TS)PetscToPointer((ts) ),
(Vec)PetscToPointer((Y) ),norm);
}
static PetscErrorCode TSStep_EIMEX(TS ts)
{
TS_EIMEX *ext = (TS_EIMEX*)ts->data;
const PetscInt ns = ext->nstages;
Vec *T=ext->T, Y=ext->Y;
SNES snes;
PetscInt i,j;
PetscBool accept = PETSC_FALSE;
PetscErrorCode ierr;
PetscReal alpha,local_error;
PetscFunctionBegin;
ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
ierr = SNESSetType(snes,"ksponly"); CHKERRQ(ierr);
ext->status = TS_STEP_INCOMPLETE;
ierr = VecCopy(ts->vec_sol,ext->VecSolPrev);CHKERRQ(ierr);
/* Apply n_j steps of the base method to obtain solutions of T(j,1),1<=j<=s*/
for(j=0; j<ns; j++){
ierr = TSStage_EIMEX(ts,j);CHKERRQ(ierr);
ierr = VecCopy(Y,T[j]); CHKERRQ(ierr);
}
for(i=1;i<ns;i++){
for(j=i;j<ns;j++){
alpha = -(PetscReal)ext->N[j]/ext->N[j-i];
ierr = VecAXPBYPCZ(T[Map(j,i,ns)],alpha,1.0,0,T[Map(j,i-1,ns)],T[Map(j-1,i-1,ns)]);/*T[j][i]=alpha*T[j][i-1]+T[j-1][i-1]*/
alpha = 1.0/(1.0 + alpha);
ierr = VecScale(T[Map(j,i,ns)],alpha);CHKERRQ(ierr);
}
}
ierr = TSEvaluateStep(ts,ns,ts->vec_sol,NULL);CHKERRQ(ierr);/*update ts solution */
if(ext->ord_adapt && ext->nstages < ext->max_rows){
accept = PETSC_FALSE;
while(!accept && ext->nstages < ext->max_rows){
ierr = TSErrorNormWRMS(ts,T[Map(ext->nstages-1,ext->nstages-2,ext->nstages)],&local_error);CHKERRQ(ierr);
accept = (local_error < 1.0)? PETSC_TRUE : PETSC_FALSE;
if(!accept){/* add one more stage*/
ierr = TSStage_EIMEX(ts,ext->nstages);CHKERRQ(ierr);
ext->nstages++; ext->row_ind++; ext->col_ind++;
/*T table need to be recycled*/
ierr = VecDuplicateVecs(ts->vec_sol,(1+ext->nstages)*ext->nstages/2,&ext->T);CHKERRQ(ierr);
for(i=0; i<ext->nstages-1; i++){
for(j=0; j<=i; j++){
ierr = VecCopy(T[Map(i,j,ext->nstages-1)],ext->T[Map(i,j,ext->nstages)]);CHKERRQ(ierr);
}
}
ierr = VecDestroyVecs(ext->nstages*(ext->nstages-1)/2,&T);CHKERRQ(ierr);
T = ext->T; /*reset the pointer*/
/*recycling finished, store the new solution*/
ierr = VecCopy(Y,T[ext->nstages-1]); CHKERRQ(ierr);
/*extrapolation for the newly added stage*/
for(i=1;i<ext->nstages;i++){
alpha = -(PetscReal)ext->N[ext->nstages-1]/ext->N[ext->nstages-1-i];
ierr = VecAXPBYPCZ(T[Map(ext->nstages-1,i,ext->nstages)],alpha,1.0,0,T[Map(ext->nstages-1,i-1,ext->nstages)],T[Map(ext->nstages-1-1,i-1,ext->nstages)]);/*T[ext->nstages-1][i]=alpha*T[ext->nstages-1][i-1]+T[ext->nstages-1-1][i-1]*/
alpha = 1.0/(1.0 + alpha);
ierr = VecScale(T[Map(ext->nstages-1,i,ext->nstages)],alpha);CHKERRQ(ierr);
}
/*update ts solution */
ierr = TSEvaluateStep(ts,ext->nstages,ts->vec_sol,NULL);CHKERRQ(ierr);
}/*end if !accept*/
}/*end while*/
if(ext->nstages == ext->max_rows){
ierr = PetscInfo(ts,"Max number of rows has been used\n");CHKERRQ(ierr);
}
}/*end if ext->ord_adapt*/
ts->ptime += ts->time_step;
ts->steps++;
ext->status = TS_STEP_COMPLETE;
if (ext->status != TS_STEP_COMPLETE && !ts->reason) ts->reason = TS_DIVERGED_STEP_REJECTED;
PetscFunctionReturn(0);
}
