PetscErrorCode KSPSetFromOptions_Chebyshev(KSP ksp)
{
KSP_Chebyshev *cheb = (KSP_Chebyshev*)ksp->data;
PetscErrorCode ierr;
PetscInt two = 2,four = 4;
PetscReal tform[4] = {PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE};
PetscBool flg;
PetscFunctionBegin;
ierr = PetscOptionsHead("KSP Chebyshev Options");CHKERRQ(ierr);
ierr = PetscOptionsInt("-ksp_chebyshev_eststeps","Number of est steps in Chebyshev","",cheb->eststeps,&cheb->eststeps,NULL);CHKERRQ(ierr);
ierr = PetscOptionsRealArray("-ksp_chebyshev_eigenvalues","extreme eigenvalues","KSPChebyshevSetEigenvalues",&cheb->emin,&two,0);CHKERRQ(ierr);
ierr = PetscOptionsRealArray("-ksp_chebyshev_estimate_eigenvalues","estimate eigenvalues using a Krylov method, then use this transform for Chebyshev eigenvalue bounds","KSPChebyshevSetEstimateEigenvalues",tform,&four,&flg);CHKERRQ(ierr);
if (flg) {
switch (four) {
case 0:
ierr = KSPChebyshevSetEstimateEigenvalues(ksp,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
break;
case 2: /* Base everything on the max eigenvalues */
ierr = KSPChebyshevSetEstimateEigenvalues(ksp,PETSC_DECIDE,tform[0],PETSC_DECIDE,tform[1]);CHKERRQ(ierr);
break;
case 4: /* Use the full 2x2 linear transformation */
ierr = KSPChebyshevSetEstimateEigenvalues(ksp,tform[0],tform[1],tform[2],tform[3]);CHKERRQ(ierr);
break;
default: SETERRQ(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_INCOMP,"Must specify either 0, 2, or 4 parameters for eigenvalue estimation");
}
}
if (cheb->kspest) {
PetscBool estrand = PETSC_FALSE;
ierr = PetscOptionsBool("-ksp_chebyshev_estimate_eigenvalues_random","Use Random right hand side for eigenvalue estimation","KSPChebyshevEstEigSetRandom",estrand,&estrand,NULL);CHKERRQ(ierr);
if (estrand) {
PetscRandom random;
ierr = PetscRandomCreate(PetscObjectComm((PetscObject)ksp),&random);CHKERRQ(ierr);
ierr = PetscObjectSetOptionsPrefix((PetscObject)random,((PetscObject)ksp)->prefix);CHKERRQ(ierr);
ierr = PetscObjectAppendOptionsPrefix((PetscObject)random,"ksp_chebyshev_estimate_eigenvalues_");CHKERRQ(ierr);
ierr = PetscRandomSetFromOptions(random);CHKERRQ(ierr);
ierr = KSPChebyshevEstEigSetRandom(ksp,random);CHKERRQ(ierr);
ierr = PetscRandomDestroy(&random);CHKERRQ(ierr);
}
}
if (cheb->kspest) {
/* Mask the PC so that PCSetFromOptions does not do anything */
ierr = KSPSetPC(cheb->kspest,cheb->pcnone);CHKERRQ(ierr);
ierr = KSPSetOptionsPrefix(cheb->kspest,((PetscObject)ksp)->prefix);CHKERRQ(ierr);
ierr = KSPAppendOptionsPrefix(cheb->kspest,"est_");CHKERRQ(ierr);
if (!((PetscObject)cheb->kspest)->type_name) {
ierr = KSPSetType(cheb->kspest,KSPGMRES);CHKERRQ(ierr);
}
ierr = KSPSetFromOptions(cheb->kspest);CHKERRQ(ierr);
ierr = KSPSetPC(cheb->kspest,ksp->pc);CHKERRQ(ierr);
}
ierr = PetscOptionsTail();CHKERRQ(ierr);
PetscFunctionReturn(0);
}
static PetscErrorCode KSPChebyshevSetEigenvalues_Chebyshev(KSP ksp,PetscReal emax,PetscReal emin)
{
KSP_Chebyshev *chebyshevP = (KSP_Chebyshev*)ksp->data;
PetscErrorCode ierr;
PetscFunctionBegin;
if (emax <= emin) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_INCOMP,"Maximum eigenvalue must be larger than minimum: max %g min %g",(double)emax,(double)emin);
if (emax*emin <= 0.0) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_INCOMP,"Both eigenvalues must be of the same sign: max %g min %g",(double)emax,(double)emin);
chebyshevP->emax = emax;
chebyshevP->emin = emin;
ierr = KSPChebyshevSetEstimateEigenvalues(ksp,0.,0.,0.,0.);CHKERRQ(ierr); /* Destroy any estimation setup */
PetscFunctionReturn(0);
}
PetscErrorCode KSPSetUp_Chebyshev(KSP ksp)
{
KSP_Chebyshev *cheb = (KSP_Chebyshev*)ksp->data;
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = KSPSetWorkVecs(ksp,3);CHKERRQ(ierr);
if (cheb->emin == 0. || cheb->emax == 0.) { /* We need to estimate eigenvalues */
ierr = KSPChebyshevSetEstimateEigenvalues(ksp,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
/* Enable runtime options for cheb->kspest:
KSPChebyshevSetEstimateEigenvalues() creates cheb->kspest, but does not call KSPSetFromOptions(cheb->kspest)! */
ierr = KSPSetFromOptions(cheb->kspest);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
void PETSC_STDCALL kspchebyshevsetestimateeigenvalues_(KSP ksp,PetscReal *a,PetscReal *b,PetscReal *c,PetscReal *d, int *__ierr ){
*__ierr = KSPChebyshevSetEstimateEigenvalues(
(KSP)PetscToPointer((ksp) ),*a,*b,*c,*d);
}
