#undef __FUNCT__
#define __FUNCT__ "KSPSolve_PREONLY"
static PetscErrorCode KSPSolve_PREONLY(KSP ksp)
{
PetscErrorCode ierr;
PetscTruth diagonalscale;
PetscFunctionBegin;
ierr = PCDiagonalScale(ksp->pc,&diagonalscale);CHKERRQ(ierr);
if (diagonalscale) SETERRQ1(PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name);
if (!ksp->guess_zero) {
SETERRQ(PETSC_ERR_USER,"Running KSP of preonly doesn't make sense with nonzero initial guess\n\
you probably want a KSP type of Richardson");
}
ksp->its = 0;
ierr = PCSetInitialGuessNonzero(ksp->pc,(PetscTruth)!(int)ksp->guess_zero);CHKERRQ(ierr);
ierr = KSP_PCApply(ksp,ksp->vec_rhs,ksp->vec_sol);CHKERRQ(ierr);
ksp->its = 1;
ksp->reason = KSP_CONVERGED_ITS;
PetscFunctionReturn(0);
}
/*MC
KSPPREONLY - This implements a stub method that applies ONLY the preconditioner.
This may be used in inner iterations, where it is desired to
allow multiple iterations as well as the "0-iteration" case. It is
commonly used with the direct solver preconditioners like PCLU and PCCHOLESKY
Options Database Keys:
. see KSPSolve()
PETSC_EXTERN void PETSC_STDCALL pcsetinitialguessnonzero_(PC pc,PetscBool *flg, int *__ierr ){
*__ierr = PCSetInitialGuessNonzero(
(PC)PetscToPointer((pc) ),*flg);
}
