MatCreateSeqBAIJ#

Creates a sparse matrix in MATSEQAIJ (block compressed row) format. For good matrix assembly performance the user should preallocate the matrix storage by setting the parameter nz (or the array nnz).

Synopsis#

#include "petscmat.h"  
PetscErrorCode MatCreateSeqBAIJ(MPI_Comm comm, PetscInt bs, PetscInt m, PetscInt n, PetscInt nz, const PetscInt nnz[], Mat *A)

Collective

Input Parameters#

comm - MPI communicator, set to PETSC_COMM_SELF
bs - size of block, the blocks are ALWAYS square. One can use MatSetBlockSizes() to set a different row and column blocksize but the row blocksize always defines the size of the blocks. The column blocksize sets the blocksize of the vectors obtained with MatCreateVecs()
m - number of rows
n - number of columns
nz - number of nonzero blocks per block row (same for all rows)
nnz - array containing the number of nonzero blocks in the various block rows (possibly different for each block row) or NULL

Output Parameter#

A - the matrix

Options Database Keys#

-mat_no_unroll - uses code that does not unroll the loops in the block calculations (much slower)
-mat_block_size - size of the blocks to use

Notes#

It is recommended that one use MatCreateFromOptions() or the MatCreate(), MatSetType() and/or MatSetFromOptions(), MatXXXXSetPreallocation() paradigm instead of this routine directly. [MatXXXXSetPreallocation() is, for example, MatSeqAIJSetPreallocation()]

The number of rows and columns must be divisible by blocksize.

If the nnz parameter is given then the nz parameter is ignored

A nonzero block is any block that as 1 or more nonzeros in it

The MATSEQBAIJ format is fully compatible with standard Fortran storage. That is, the stored row and column indices can begin at either one (as in Fortran) or zero.

Specify the preallocated storage with either nz or nnz (not both). Set nz = PETSC_DEFAULT and nnz = NULL for PETSc to control dynamic memory allocation. See Sparse Matrices for details. matrices.