# MatZeroRowsColumnsLocal
Zeros all entries (except possibly the main diagonal) of a set of rows and columns of a matrix; using local numbering of rows. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatZeroRowsColumnsLocal(Mat mat, PetscInt numRows, const PetscInt rows[], PetscScalar diag, Vec x, Vec b)
```
Collective


## Input Parameters

- ***mat -*** the matrix
- ***numRows -*** the number of rows to remove
- ***rows -*** the global row indices
- ***diag -*** value put in all diagonals of eliminated rows
- ***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





## Notes
Before calling `MatZeroRowsColumnsLocal()`, the user must first set the
local-to-global mapping by calling `MatSetLocalToGlobalMapping()`, this is often already set for matrices obtained with `DMCreateMatrix()`.

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


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

## Level
intermediate

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


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