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# MatGetBlockSizes
Returns the matrix block row and column sizes. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatGetBlockSizes(Mat mat, PetscInt *rbs, PetscInt *cbs)
```
Not Collective


## Input Parameter

- ***mat -*** the matrix



## Output Parameters

- ***rbs -*** row block size
- ***cbs -*** column block size





## Notes
Block row formats are `MATBAIJ` and `MATSBAIJ` ALWAYS have square block storage in the matrix.
If you pass a different block size for the columns than the rows, the row block size determines the square block storage.

If a block size has not been set yet this routine returns 1.


## See Also
 [](ch_matrices), `Mat`, `MATBAIJ`, `MATSBAIJ`, `MatCreateSeqBAIJ()`, `MatCreateBAIJ()`, `MatGetBlockSize()`, `MatSetBlockSize()`, `MatSetBlockSizes()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matrix.c.html#MatGetBlockSizes">src/mat/interface/matrix.c</A>


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