/*@
MatSchurComplementComputeExplicitOperator - Compute the Schur complement matrix explicitly
Collective on Mat
Input Parameter:
. M - the matrix obtained with MatCreateSchurComplement()
Output Parameter:
. S - the Schur complement matrix
Note: This can be expensive, so it is mainly for testing
Level: advanced
.seealso: MatCreateSchurComplement(), MatSchurComplementUpdate()
@*/
PetscErrorCode MatSchurComplementComputeExplicitOperator(Mat M, Mat *S)
{
Mat B, C, D;
KSP ksp;
PC pc;
PetscBool isLU, isILU;
PetscReal fill = 2.0;
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = MatSchurComplementGetSubMatrices(M, NULL, NULL, &B, &C, &D);CHKERRQ(ierr);
ierr = MatSchurComplementGetKSP(M, &ksp);CHKERRQ(ierr);
ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
ierr = PetscObjectTypeCompare((PetscObject) pc, PCLU, &isLU);CHKERRQ(ierr);
ierr = PetscObjectTypeCompare((PetscObject) pc, PCILU, &isILU);CHKERRQ(ierr);
if (isLU || isILU) {
Mat fact, Bd, AinvB, AinvBd;
PetscReal eps = 1.0e-10;
/* This can be sped up for banded LU */
ierr = KSPSetUp(ksp);CHKERRQ(ierr);
ierr = PCFactorGetMatrix(pc, &fact);CHKERRQ(ierr);
ierr = MatConvert(B, MATDENSE, MAT_INITIAL_MATRIX, &Bd);CHKERRQ(ierr);
ierr = MatDuplicate(Bd, MAT_DO_NOT_COPY_VALUES, &AinvBd);CHKERRQ(ierr);
ierr = MatMatSolve(fact, Bd, AinvBd);CHKERRQ(ierr);
ierr = MatDestroy(&Bd);CHKERRQ(ierr);
ierr = MatChop(AinvBd, eps);CHKERRQ(ierr);
ierr = MatConvert(AinvBd, MATAIJ, MAT_INITIAL_MATRIX, &AinvB);CHKERRQ(ierr);
ierr = MatDestroy(&AinvBd);CHKERRQ(ierr);
ierr = MatMatMult(C, AinvB, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
ierr = MatDestroy(&AinvB);CHKERRQ(ierr);
} else {
Mat Ainvd, Ainv;
ierr = PCComputeExplicitOperator(pc, &Ainvd);CHKERRQ(ierr);
ierr = MatConvert(Ainvd, MATAIJ, MAT_INITIAL_MATRIX, &Ainv);CHKERRQ(ierr);
ierr = MatDestroy(&Ainvd);CHKERRQ(ierr);
#if 0
/* Symmetric version */
ierr = MatPtAP(Ainv, B, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
#else
/* Nonsymmetric version */
ierr = MatMatMatMult(C, Ainv, B, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
#endif
ierr = MatDestroy(&Ainv);CHKERRQ(ierr);
}
ierr = PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO);CHKERRQ(ierr);
ierr = MatView(*S, PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
ierr = PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
if (D) {
MatInfo info;
ierr = MatGetInfo(D, MAT_GLOBAL_SUM, &info);CHKERRQ(ierr);
if (info.nz_used) SETERRQ(PetscObjectComm((PetscObject) M), PETSC_ERR_SUP, "Not yet implemented");
}
PetscFunctionReturn(0);
}
/*@
MatSchurComplementComputeExplicitOperator - Compute the Schur complement matrix explicitly
Collective on Mat
Input Parameter:
. M - the matrix obtained with MatCreateSchurComplement()
Output Parameter:
. S - the Schur complement matrix
Note: This can be expensive, so it is mainly for testing
Level: advanced
.seealso: MatCreateSchurComplement(), MatSchurComplementUpdate()
@*/
PetscErrorCode MatSchurComplementComputeExplicitOperator(Mat M, Mat *S)
{
Mat B, C, D;
KSP ksp;
PC pc;
PetscBool isLU, isILU;
PetscReal fill = 2.0;
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = MatSchurComplementGetSubMatrices(M, NULL, NULL, &B, &C, &D);CHKERRQ(ierr);
ierr = MatSchurComplementGetKSP(M, &ksp);CHKERRQ(ierr);
ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
ierr = PetscObjectTypeCompare((PetscObject) pc, PCLU, &isLU);CHKERRQ(ierr);
ierr = PetscObjectTypeCompare((PetscObject) pc, PCILU, &isILU);CHKERRQ(ierr);
if (isLU || isILU) {
Mat fact, Bd, AinvB, AinvBd;
PetscReal eps = 1.0e-10;
/* This can be sped up for banded LU */
ierr = KSPSetUp(ksp);CHKERRQ(ierr);
ierr = PCFactorGetMatrix(pc, &fact);CHKERRQ(ierr);
ierr = MatConvert(B, MATDENSE, MAT_INITIAL_MATRIX, &Bd);CHKERRQ(ierr);
ierr = MatDuplicate(Bd, MAT_DO_NOT_COPY_VALUES, &AinvBd);CHKERRQ(ierr);
ierr = MatMatSolve(fact, Bd, AinvBd);CHKERRQ(ierr);
ierr = MatDestroy(&Bd);CHKERRQ(ierr);
ierr = MatChop(AinvBd, eps);CHKERRQ(ierr);
ierr = MatConvert(AinvBd, MATAIJ, MAT_INITIAL_MATRIX, &AinvB);CHKERRQ(ierr);
ierr = MatDestroy(&AinvBd);CHKERRQ(ierr);
ierr = MatMatMult(C, AinvB, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
ierr = MatDestroy(&AinvB);CHKERRQ(ierr);
} else {
Mat Ainvd, Ainv;
ierr = PCComputeExplicitOperator(pc, &Ainvd);CHKERRQ(ierr);
ierr = MatConvert(Ainvd, MATAIJ, MAT_INITIAL_MATRIX, &Ainv);CHKERRQ(ierr);
ierr = MatDestroy(&Ainvd);CHKERRQ(ierr);
#if 0
/* Symmetric version */
ierr = MatPtAP(Ainv, B, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
#else
/* Nonsymmetric version */
ierr = MatMatMatMult(C, Ainv, B, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
#endif
ierr = MatDestroy(&Ainv);CHKERRQ(ierr);
}
if (D) {
ierr = MatAXPY(*S, -1.0, D, DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
}
ierr = MatScale(*S,-1.0);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
