# MatZeroRowsColumnsIS
Zeros all entries (except possibly the main diagonal) of a set of rows and columns of a matrix. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatZeroRowsColumnsIS(Mat mat, IS is, PetscScalar diag, Vec x, Vec b)
```
Collective


## Input Parameters

- ***mat -*** the matrix
- ***is -*** the rows to zero
- ***diag -*** value put in all diagonals of eliminated rows (0.0 will even eliminate diagonal entry)
- ***x -*** optional vector of solutions for zeroed rows (other entries in vector are not used)
- ***b -*** optional vector of right hand side, that will be adjusted by provided solution





## Note
See `MatZeroRowsColumns()` for details on how this routine operates.


## See Also
 `Mat`, `MatZeroRowsIS()`, `MatZeroRowsColumns()`, `MatZeroRowsLocalIS()`, `MatZeroRowsStencil()`, `MatZeroEntries()`, `MatZeroRowsLocal()`, `MatSetOption()`,
`MatZeroRowsColumnsLocal()`, `MatZeroRowsColumnsLocalIS()`, `MatZeroRows()`, `MatZeroRowsColumnsStencil()`

## Level
intermediate

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex71.c.html">src/ksp/ksp/tutorials/ex71.c.html</A><BR>


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