Skip to main content
`Ctrl`+`K`

# MatMPIBAIJSetPreallocationCSR

Creates a sparse parallel matrix in `MATBAIJ` format using the given nonzero structure and (optional) numerical values

## Synopsis

    #include "petscmat.h"
    PetscErrorCode MatMPIBAIJSetPreallocationCSR(Mat B, PetscInt bs, const PetscInt i[], const PetscInt j[], const PetscScalar v[])

Collective

## Input Parameters

- B - the matrix

- bs - the block size

- i - the indices into `j` for the start of each local row (starts with zero)

- j - the column indices for each local row (starts with zero) these must be sorted for each row

- v - optional values in the matrix, use `NULL` if not provided

## Notes

The `i`, `j`, and `v` arrays ARE copied by this routine into the internal format used by PETSc; thus you CANNOT change the matrix entries by changing the values of `v` after you have called this routine.

The order of the entries in values is specified by the `MatOption` `MAT_ROW_ORIENTED`. For example, C programs may want to use the default `MAT_ROW_ORIENTED` with value `PETSC_TRUE` and use an array v[nnz][bs][bs] where the second index is over rows within a block and the last index is over columns within a block row. Fortran programs will likely set `MAT_ROW_ORIENTED` with value `PETSC_FALSE` and use a Fortran array v(bs,bs,nnz) in which the first index is over rows within a block column and the second index is over columns within a block.

Though this routine has Preallocation() in the name it also sets the exact nonzero locations of the matrix entries and usually the numerical values as well

## See Also

`Mat`, `MatCreate()`, `MatCreateSeqAIJ()`, `MatSetValues()`, `MatMPIBAIJSetPreallocation()`, `MatCreateAIJ()`, `MATMPIAIJ`, `MatCreateMPIBAIJWithArrays()`, `MATMPIBAIJ`

## Level

advanced

## Location

src/mat/impls/baij/mpi/mpibaij.c

## Implementations

MatMPIBAIJSetPreallocationCSR_MPIBAIJ() in src/mat/impls/baij/mpi/mpibaij.c

Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages