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# KSPComputeOperator
Computes the explicit preconditioned operator, including diagonal scaling and null space removal if applicable. 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode KSPComputeOperator(KSP ksp, MatType mattype, Mat *mat)
```
Collective


## Input Parameters

- ***ksp -*** the Krylov subspace context
- ***mattype -*** the matrix type to be used



## Output Parameter

- ***mat -*** the explicit preconditioned operator



## Notes
This computation is done by applying the operators to columns of the
identity matrix.

Currently, this routine uses a dense matrix format for the output operator if mattype == NULL.
This routine is costly in general, and is recommended for use only with relatively small systems.




## See Also
 [](ch_ksp), `KSP`, `KSPSetOperators()`, `KSPComputeEigenvaluesExplicitly()`, `PCComputeOperator()`, `KSPSetDiagonalScale()`, `KSPSetNullSpace()`, `MatType`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/interface/eige.c.html#KSPComputeOperator">src/ksp/ksp/interface/eige.c</A>


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[Index of all KSP routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)