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# MatScaLAPACKSetBlockSizes
Sets the block sizes to be used for the distribution of the `MATSCALAPACK` matrix 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatScaLAPACKSetBlockSizes(Mat A, PetscInt mb, PetscInt nb)
```
Logically Collective


## Input Parameters

- ***A  -*** a `MATSCALAPACK` matrix
- ***mb -*** the row block size
- ***nb -*** the column block size





## Note
This block size has a different meaning from the block size associated with `MatSetBlockSize()` used for sparse matrices


## See Also
 [](ch_matrices), `Mat`, `MATSCALAPACK`, `MatCreateScaLAPACK()`, `MatScaLAPACKGetBlockSizes()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/scalapack/matscalapack.c.html#MatScaLAPACKSetBlockSizes">src/mat/impls/scalapack/matscalapack.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/scalapack/matscalapack.c.html#MatScaLAPACKSetBlockSizes_ScaLAPACK">MatScaLAPACKSetBlockSizes_ScaLAPACK in src/mat/impls/scalapack/matscalapack.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/impls/scalapack/matscalapack.c)


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