petsc-3.4.4 2014-03-13

MatCreateSeqSBAIJ

Creates a sparse symmetric matrix in block AIJ (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). By setting these parameters accurately, performance during matrix assembly can be increased by more than a factor of 50.

Synopsis

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

Input Parameters

comm - MPI communicator, set to PETSC_COMM_SELF
bs - size of block
m - number of rows, or number of columns
nz - number of block nonzeros per block row (same for all rows)
nnz - array containing the number of block nonzeros in the upper triangular plus diagonal portion of each block (possibly different for each block row) or NULL

Output Parameter

A -the symmetric 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

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

Notes

The number of rows and columns must be divisible by blocksize. This matrix type does not support complex Hermitian operation.

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 the <a href="../../docs/manual.pdf#nameddest=ch_mat">Mat chapter of the users manual</a> for details.

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

See Also

MatCreate(), MatCreateSeqAIJ(), MatSetValues(), MatCreateSBAIJ()

Level:intermediate
Location:
src/mat/impls/sbaij/seq/sbaij.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages