MatCheckCompressedRow#

Determines whether the compressed row matrix format should be used. Compressed row format provides high performance routines by taking advantage of zero rows.

Synopsis#

#include "petscmat.h"  
PETSC_EXTERN PetscErrorCode MatCheckCompressedRow(Mat A, PetscInt nrows, Mat_CompressedRow *compressedrow, PetscInt *ai, PetscInt mbs, PetscReal ratio)

Collective

Input Parameters#

A - the matrix
nrows - number of rows with nonzero entries
compressedrow - pointer to the struct Mat_CompressedRow
ai - row pointer used by MATSEQAIJ and MATSEQBAIJ
mbs - number of (block) rows represented by ai
ratio - ratio of (num of zero rows)/m, used to determine if the compressed row format should be used

Note#

Supported types are MATAIJ, MATBAIJ and MATSBAIJ.

Developer Notes#

The reason this takes the compressedrow, ai and mbs arguments is because it is called by both the MATSEQAIJ and MATSEQBAIJ matrices and the values are not therefore obtained by directly taking the values from the matrix object. This is not a general public routine and hence is not listed in petscmat.h (it exposes a private data structure) but it is used by some preconditioners and hence is labeled as PETSC_EXTERN

Level#

developer

Location#

src/mat/utils/compressedrow.c

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