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# PCDeflationSetProjectionNullSpaceMat
Set the projection null space matrix (W'*A). 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode PCDeflationSetProjectionNullSpaceMat(PC pc, Mat mat)
```
Collective


## Input Parameters

- ***pc  -*** preconditioner context
- ***mat -*** projection null space matrix





## See Also
 `PCDEFLATION`, `PCDeflationSetSpace()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/deflation/deflation.c.html#PCDeflationSetProjectionNullSpaceMat">src/ksp/pc/impls/deflation/deflation.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/deflation/deflation.c.html#PCDeflationSetProjectionNullSpaceMat_Deflation">PCDeflationSetProjectionNullSpaceMat_Deflation in src/ksp/pc/impls/deflation/deflation.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/pc/impls/deflation/deflation.c)


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