:orphan:
# MatDenseGetSubMatrix
Gives access to a block of rows and columns of a dense matrix, represented as a Mat. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatDenseGetSubMatrix(Mat A, PetscInt rbegin, PetscInt rend, PetscInt cbegin, PetscInt cend, Mat *v)
```
Collective


## Input Parameters

- ***mat -*** the Mat object
- ***rbegin -*** the first global row index in the block (if `PETSC_DECIDE`, is 0)
- ***rend -*** the global row index past the last one in the block (if `PETSC_DECIDE`, is `M`)
- ***cbegin -*** the first global column index in the block (if `PETSC_DECIDE`, is 0)
- ***cend -*** the global column index past the last one in the block (if `PETSC_DECIDE`, is `N`)



## Output Parameter

- ***v -*** the matrix





## Notes
The matrix is owned by PETSc. Users need to call `MatDenseRestoreSubMatrix()` when the matrix is no longer needed.

The output matrix is not redistributed by PETSc, so depending on the values of `rbegin` and `rend`, some processes may have no local rows.


## See Also
 [](ch_matrices), `Mat`, `MATDENSE`, `MATDENSECUDA`, `MATDENSEHIP`, `MatDenseGetColumnVec()`, `MatDenseRestoreColumnVec()`, `MatDenseRestoreSubMatrix()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/seq/dense.c.html#MatDenseGetSubMatrix">src/mat/impls/dense/seq/dense.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/mpi/mpidense.c.html#MatDenseGetSubMatrix_MPIDense">MatDenseGetSubMatrix_MPIDense in src/mat/impls/dense/mpi/mpidense.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/seq/dense.c.html#MatDenseGetSubMatrix_SeqDense">MatDenseGetSubMatrix_SeqDense in src/mat/impls/dense/seq/dense.c</A><BR>


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