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# MatFindNonzeroRows
Locate all rows that are not completely zero in the matrix 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatFindNonzeroRows(Mat mat, IS *keptrows)
```

## Input Parameter

- ***A  -*** the matrix



## Output Parameter

- ***keptrows -*** the rows that are not completely zero





## Note
`keptrows` is set to `NULL` if all rows are nonzero.


## See Also
 [](ch_matrices), `Mat`, `MatFindZeroRows()`

## Level
intermediate

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

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mpiaij.c.html#MatFindNonzeroRows_MPIAIJ">MatFindNonzeroRows_MPIAIJ in src/mat/impls/aij/mpi/mpiaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/aij.c.html#MatFindNonzeroRows_SeqAIJ">MatFindNonzeroRows_SeqAIJ in src/mat/impls/aij/seq/aij.c</A><BR>


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