MatSchurComplementGetPmat#
Obtain a preconditioning matrix for the Schur complement by assembling Sp = A11 - A10 inv(DIAGFORM(A00)) A01
Synopsis#
#include "petscksp.h"
PetscErrorCode MatSchurComplementGetPmat(Mat S, MatReuse preuse, Mat *Sp)
Collective on S
Input Parameters#
S - matrix obtained with MatCreateSchurComplement() (or equivalent) that implements the action of A11 - A10 ksp(A00,Ap00) A01
preuse - MAT_INITIAL_MATRIX for a new Sp, or MAT_REUSE_MATRIX to reuse an existing Sp, or MAT_IGNORE_MATRIX to put nothing in Sp
Output Parameter#
Sp - approximate Schur complement suitable for preconditioning the exact Schur complement S = A11 - A10 inv(A00) A01
Note#
The approximation of Sp depends on the the argument passed to to MatSchurComplementSetAinvType() MAT_SCHUR_COMPLEMENT_AINV_DIAG, MAT_SCHUR_COMPLEMENT_AINV_LUMP, MAT_SCHUR_COMPLEMENT_AINV_BLOCK_DIAG, or MAT_SCHUR_COMPLEMENT_AINV_FULL -mat_schur_complement_ainv_type <diag,lump,blockdiag,full>
Sometimes users would like to provide problem-specific data in the Schur complement, usually only for special row and column index sets. In that case, the user should call PetscObjectComposeFunction() to set “MatSchurComplementGetPmat_C” to their function. If their function needs to fall back to the default implementation, it should call MatSchurComplementGetPmat_Basic().
Developer Notes#
The API that includes MatGetSchurComplement(), MatCreateSchurComplement(), MatSchurComplementGetPmat() should be refactored to remove redundancy and be clearer and simpler.
This routine should be called MatSchurComplementCreatePmat()
See Also#
MatCreateSubMatrix()
, PCFIELDSPLIT
, MatGetSchurComplement()
, MatCreateSchurComplement()
, MatSchurComplementSetAinvType()
Level#
advanced
Location#
src/ksp/ksp/utils/schurm/schurm.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages