#include "petscksp.h" PetscErrorCode MatGetSchurComplement(Mat mat,IS isrow0,IS iscol0,IS isrow1,IS iscol1,MatReuse mreuse,Mat *newmat,MatReuse preuse,Mat *newpmat)Collective on Mat
mat | - Matrix in which the complement is to be taken | |
isrow0 | - rows to eliminate | |
iscol0 | - columns to eliminate, (isrow0,iscol0) should be square and nonsingular | |
isrow1 | - rows in which the Schur complement is formed | |
iscol1 | - columns in which the Schur complement is formed | |
mreuse | - MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX, use MAT_IGNORE_MATRIX to put nothing in newmat | |
preuse | - MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX, use MAT_IGNORE_MATRIX to put nothing in newpmat |
newmat | - exact Schur complement, often of type MATSCHURCOMPLEMENT which is difficult to use for preconditioning | |
newpmat | - approximate Schur complement suitable for preconditioning |
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 "MatNestGetSubMat_C" to their function. If their function needs to fall back to the default implementation, it should call MatGetSchurComplement_Basic().
Level:advanced
Location:src/ksp/ksp/utils/schurm.c
Index of all KSP routines
Table of Contents for all manual pages
Index of all manual pages