static PetscErrorCode PCApply_MG(PC pc,Vec b,Vec x)
{
PC_MG *mg = (PC_MG*)pc->data;
PC_MG_Levels **mglevels = mg->levels;
PetscErrorCode ierr;
PetscInt levels = mglevels[0]->levels,i;
PetscFunctionBegin;
if (mg->stageApply) {ierr = PetscLogStagePush(mg->stageApply);CHKERRQ(ierr);}
/* When the DM is supplying the matrix then it will not exist until here */
for (i=0; i<levels; i++) {
if (!mglevels[i]->A) {
ierr = KSPGetOperators(mglevels[i]->smoothu,&mglevels[i]->A,NULL);CHKERRQ(ierr);
ierr = PetscObjectReference((PetscObject)mglevels[i]->A);CHKERRQ(ierr);
}
}
mglevels[levels-1]->b = b;
mglevels[levels-1]->x = x;
if (mg->am == PC_MG_MULTIPLICATIVE) {
ierr = VecSet(x,0.0);CHKERRQ(ierr);
for (i=0; i<mg->cyclesperpcapply; i++) {
ierr = PCMGMCycle_Private(pc,mglevels+levels-1,NULL);CHKERRQ(ierr);
}
} else if (mg->am == PC_MG_ADDITIVE) {
ierr = PCMGACycle_Private(pc,mglevels);CHKERRQ(ierr);
} else if (mg->am == PC_MG_KASKADE) {
ierr = PCMGKCycle_Private(pc,mglevels);CHKERRQ(ierr);
} else {
ierr = PCMGFCycle_Private(pc,mglevels);CHKERRQ(ierr);
}
if (mg->stageApply) {ierr = PetscLogStagePop();CHKERRQ(ierr);}
PetscFunctionReturn(0);
}
PetscErrorCode PCMGMCycle_Private(PC pc,PC_MG_Levels **mglevelsin,PCRichardsonConvergedReason *reason)
{
PC_MG *mg = (PC_MG*)pc->data;
PC_MG_Levels *mgc,*mglevels = *mglevelsin;
PetscErrorCode ierr;
PetscInt cycles = (mglevels->level == 1) ? 1 : (PetscInt) mglevels->cycles;
PC subpc;
PCFailedReason pcreason;
PetscFunctionBegin;
if (mglevels->eventsmoothsolve) {ierr = PetscLogEventBegin(mglevels->eventsmoothsolve,0,0,0,0);CHKERRQ(ierr);}
ierr = KSPSolve(mglevels->smoothd,mglevels->b,mglevels->x);CHKERRQ(ierr); /* pre-smooth */
ierr = KSPGetPC(mglevels->smoothd,&subpc);CHKERRQ(ierr);
ierr = PCGetSetUpFailedReason(subpc,&pcreason);CHKERRQ(ierr);
if (pcreason) {
pc->failedreason = PC_SUBPC_ERROR;
}
if (mglevels->eventsmoothsolve) {ierr = PetscLogEventEnd(mglevels->eventsmoothsolve,0,0,0,0);CHKERRQ(ierr);}
if (mglevels->level) { /* not the coarsest grid */
if (mglevels->eventresidual) {ierr = PetscLogEventBegin(mglevels->eventresidual,0,0,0,0);CHKERRQ(ierr);}
ierr = (*mglevels->residual)(mglevels->A,mglevels->b,mglevels->x,mglevels->r);CHKERRQ(ierr);
if (mglevels->eventresidual) {ierr = PetscLogEventEnd(mglevels->eventresidual,0,0,0,0);CHKERRQ(ierr);}
/* if on finest level and have convergence criteria set */
if (mglevels->level == mglevels->levels-1 && mg->ttol && reason) {
PetscReal rnorm;
ierr = VecNorm(mglevels->r,NORM_2,&rnorm);CHKERRQ(ierr);
if (rnorm <= mg->ttol) {
if (rnorm < mg->abstol) {
*reason = PCRICHARDSON_CONVERGED_ATOL;
ierr = PetscInfo2(pc,"Linear solver has converged. Residual norm %g is less than absolute tolerance %g\n",(double)rnorm,(double)mg->abstol);CHKERRQ(ierr);
} else {
*reason = PCRICHARDSON_CONVERGED_RTOL;
ierr = PetscInfo2(pc,"Linear solver has converged. Residual norm %g is less than relative tolerance times initial residual norm %g\n",(double)rnorm,(double)mg->ttol);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
}
mgc = *(mglevelsin - 1);
if (mglevels->eventinterprestrict) {ierr = PetscLogEventBegin(mglevels->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
ierr = MatRestrict(mglevels->restrct,mglevels->r,mgc->b);CHKERRQ(ierr);
if (mglevels->eventinterprestrict) {ierr = PetscLogEventEnd(mglevels->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
ierr = VecSet(mgc->x,0.0);CHKERRQ(ierr);
while (cycles--) {
ierr = PCMGMCycle_Private(pc,mglevelsin-1,reason);CHKERRQ(ierr);
}
if (mglevels->eventinterprestrict) {ierr = PetscLogEventBegin(mglevels->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
ierr = MatInterpolateAdd(mglevels->interpolate,mgc->x,mglevels->x,mglevels->x);CHKERRQ(ierr);
if (mglevels->eventinterprestrict) {ierr = PetscLogEventEnd(mglevels->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
if (mglevels->eventsmoothsolve) {ierr = PetscLogEventBegin(mglevels->eventsmoothsolve,0,0,0,0);CHKERRQ(ierr);}
ierr = KSPSolve(mglevels->smoothu,mglevels->b,mglevels->x);CHKERRQ(ierr); /* post smooth */
if (mglevels->eventsmoothsolve) {ierr = PetscLogEventEnd(mglevels->eventsmoothsolve,0,0,0,0);CHKERRQ(ierr);}
}
PetscFunctionReturn(0);
}
static PetscErrorCode PCApplyRichardson_MG(PC pc,Vec b,Vec x,Vec w,PetscReal rtol,PetscReal abstol, PetscReal dtol,PetscInt its,PetscBool zeroguess,PetscInt *outits,PCRichardsonConvergedReason *reason)
{
PC_MG *mg = (PC_MG*)pc->data;
PC_MG_Levels **mglevels = mg->levels;
PetscErrorCode ierr;
PetscInt levels = mglevels[0]->levels,i;
PetscFunctionBegin;
/* When the DM is supplying the matrix then it will not exist until here */
for (i=0; i<levels; i++) {
if (!mglevels[i]->A) {
ierr = KSPGetOperators(mglevels[i]->smoothu,&mglevels[i]->A,NULL);CHKERRQ(ierr);
ierr = PetscObjectReference((PetscObject)mglevels[i]->A);CHKERRQ(ierr);
}
}
mglevels[levels-1]->b = b;
mglevels[levels-1]->x = x;
mg->rtol = rtol;
mg->abstol = abstol;
mg->dtol = dtol;
if (rtol) {
/* compute initial residual norm for relative convergence test */
PetscReal rnorm;
if (zeroguess) {
ierr = VecNorm(b,NORM_2,&rnorm);CHKERRQ(ierr);
} else {
ierr = (*mglevels[levels-1]->residual)(mglevels[levels-1]->A,b,x,w);CHKERRQ(ierr);
ierr = VecNorm(w,NORM_2,&rnorm);CHKERRQ(ierr);
}
mg->ttol = PetscMax(rtol*rnorm,abstol);
} else if (abstol) mg->ttol = abstol;
else mg->ttol = 0.0;
/* since smoother is applied to full system, not just residual we need to make sure that smoothers don't
stop prematurely due to small residual */
for (i=1; i<levels; i++) {
ierr = KSPSetTolerances(mglevels[i]->smoothu,0,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
if (mglevels[i]->smoothu != mglevels[i]->smoothd) {
ierr = KSPSetTolerances(mglevels[i]->smoothd,0,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
}
}
*reason = (PCRichardsonConvergedReason)0;
for (i=0; i<its; i++) {
ierr = PCMGMCycle_Private(pc,mglevels+levels-1,reason);CHKERRQ(ierr);
if (*reason) break;
}
if (!*reason) *reason = PCRICHARDSON_CONVERGED_ITS;
*outits = i;
PetscFunctionReturn(0);
}
PetscErrorCode PCMGFCycle_Private(PC pc,PC_MG_Levels **mglevels)
{
PetscErrorCode ierr;
PetscInt i,l = mglevels[0]->levels;
PetscFunctionBegin;
/* restrict the RHS through all levels to coarsest. */
for (i=l-1; i>0; i--){
if (mglevels[i]->eventinterprestrict) {ierr = PetscLogEventBegin(mglevels[i]->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
ierr = MatRestrict(mglevels[i]->restrct,mglevels[i]->b,mglevels[i-1]->b);CHKERRQ(ierr);
if (mglevels[i]->eventinterprestrict) {ierr = PetscLogEventEnd(mglevels[i]->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
}
/* work our way up through the levels */
ierr = VecSet(mglevels[0]->x,0.0);CHKERRQ(ierr);
for (i=0; i<l-1; i++) {
ierr = PCMGMCycle_Private(pc,&mglevels[i],PETSC_NULL);CHKERRQ(ierr);
if (mglevels[i+1]->eventinterprestrict) {ierr = PetscLogEventBegin(mglevels[i+1]->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
ierr = MatInterpolate(mglevels[i+1]->interpolate,mglevels[i]->x,mglevels[i+1]->x);CHKERRQ(ierr);
if (mglevels[i+1]->eventinterprestrict) {ierr = PetscLogEventEnd(mglevels[i+1]->eventinterprestrict,0,0,0,0);CHKERRQ(ierr);}
}
ierr = PCMGMCycle_Private(pc,&mglevels[l-1],PETSC_NULL);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
