/*@C
DMMGSetNullSpace - Indicates the null space in the linear operator (this is needed by the linear solver)
Collective on DMMG
Input Parameter:
+ dmmg - the context
. has_cnst - is the constant vector in the null space
. n - number of null vectors (excluding the possible constant vector)
- func - a function that fills an array of vectors with the null vectors (must be orthonormal), may be PETSC_NULL
Level: advanced
.seealso DMMGCreate(), DMMGDestroy, DMMGSetDM(), DMMGSolve(), MatNullSpaceCreate(), KSPSetNullSpace(), DMMGSetMatType()
@*/
PetscErrorCode PETSCSNES_DLLEXPORT DMMGSetNullSpace(DMMG *dmmg,PetscTruth has_cnst,PetscInt n,PetscErrorCode (*func)(DMMG,Vec[]))
{
PetscErrorCode ierr;
PetscInt i,j,nlevels = dmmg[0]->nlevels;
Vec *nulls = 0;
MatNullSpace nullsp;
KSP iksp;
PC pc,ipc;
PetscTruth ismg,isred;
PetscFunctionBegin;
if (!dmmg) SETERRQ(PETSC_ERR_ARG_NULL,"Passing null as DMMG");
if (!dmmg[0]->ksp) SETERRQ(PETSC_ERR_ORDER,"Must call AFTER DMMGSetKSP() or DMMGSetSNES()");
if ((n && !func) || (!n && func)) SETERRQ(PETSC_ERR_ARG_INCOMP,"Both n and func() must be set together");
if (n < 0) SETERRQ1(PETSC_ERR_ARG_OUTOFRANGE,"Cannot have negative number of vectors in null space n = %D",n)
for (i=0; i<nlevels; i++) {
if (n) {
ierr = VecDuplicateVecs(dmmg[i]->b,n,&nulls);CHKERRQ(ierr);
ierr = (*func)(dmmg[i],nulls);CHKERRQ(ierr);
}
ierr = MatNullSpaceCreate(dmmg[i]->comm,has_cnst,n,nulls,&nullsp);CHKERRQ(ierr);
ierr = KSPSetNullSpace(dmmg[i]->ksp,nullsp);CHKERRQ(ierr);
for (j=i; j<nlevels; j++) {
ierr = KSPGetPC(dmmg[j]->ksp,&pc);CHKERRQ(ierr);
ierr = PetscTypeCompare((PetscObject)pc,PCMG,&ismg);CHKERRQ(ierr);
if (ismg) {
ierr = PCMGGetSmoother(pc,i,&iksp);CHKERRQ(ierr);
ierr = KSPSetNullSpace(iksp, nullsp);CHKERRQ(ierr);
}
}
ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr);
if (n) {
ierr = VecDestroyVecs(nulls,n);CHKERRQ(ierr);
}
}
/* make all the coarse grid solvers have LU shift since they are singular */
for (i=0; i<nlevels; i++) {
ierr = KSPGetPC(dmmg[i]->ksp,&pc);CHKERRQ(ierr);
ierr = PetscTypeCompare((PetscObject)pc,PCMG,&ismg);CHKERRQ(ierr);
if (ismg) {
ierr = PCMGGetSmoother(pc,0,&iksp);CHKERRQ(ierr);
ierr = KSPGetPC(iksp,&ipc);CHKERRQ(ierr);
ierr = PetscTypeCompare((PetscObject)ipc,PCREDUNDANT,&isred);CHKERRQ(ierr);
if (isred) {
ierr = PCRedundantGetPC(ipc,&ipc);CHKERRQ(ierr);
}
ierr = PCFactorSetShiftType(ipc,MAT_SHIFT_POSITIVE_DEFINITE);CHKERRQ(ierr);
}
}
PetscFunctionReturn(0);
}
MGSolver_PETScData* MultigridSolver_CreateCoarseSolver( MultigridSolver* self, Mat matrix ) {
//MatrixSolver* coarseSolver;
MGSolver_PETScData* courseSolver;
unsigned nProcs;
PC pc;
MPI_Comm_size( self->mgData->comm, (int*)&nProcs );
/*
coarseSolver = (MatrixSolver*)PETScMatrixSolver_New( "" );
PETScMatrixSolver_SetKSPType( coarseSolver,
PETScMatrixSolver_KSPType_PreOnly );
if( nProcs == 1 ) {
PETScMatrixSolver_SetPCType( coarseSolver,
PETScMatrixSolver_PCType_LU );
}
else {
PETScMatrixSolver_SetPCType( coarseSolver,
PETScMatrixSolver_PCType_RedundantLU );
}
MatrixSolver_SetMatrix( coarseSolver, matrix );
*/
if( nProcs == 1 ){
KSPCreate( MPI_COMM_WORLD, &courseSolver->ksp );
KSPSetType( courseSolver->ksp, KSPPREONLY );
KSPGetPC( courseSolver->ksp, &pc );
PCSetType( pc, PCLU );
}
else {
PCSetType( pc, PCREDUNDANT );
#if ((PETSC_VERSION_MAJOR>=3) && (PETSC_VERSION_MINOR>=2) )
PCCreate( MPI_COMM_WORLD, &pc);
PCRedundantGetKSP( pc, &courseSolver->ksp );
#else
KSPCreate( MPI_COMM_WORLD, &courseSolver->ksp );
KSPSetType( courseSolver->ksp, KSPPREONLY );
KSPGetPC( courseSolver->ksp, &pc );
PCRedundantGetPC( pc, &pc );
#endif
PCSetType( pc, PCLU );
}
if( courseSolver->matrix != PETSC_NULL ){
Stg_MatDestroy(&courseSolver->matrix );}
courseSolver->matrix = matrix;
Stg_KSPSetOperators( courseSolver->ksp, matrix, matrix, DIFFERENT_NONZERO_PATTERN );
return courseSolver;
}
void PETSC_STDCALL pcredundantgetpc_(PC pc,PC *innerpc, int *__ierr ){
*__ierr = PCRedundantGetPC(
(PC)PetscToPointer((pc) ),innerpc);
}
