# MatPartitioningChacoSetEigenSolver
Set the eigensolver method for Chaco partitioner. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatPartitioningChacoSetEigenSolver(MatPartitioning part, MPChacoEigenType method)
```
Collective


## Input Parameters

- ***part -*** the partitioning context
- ***method -*** one of `MP_CHACO_LANCZOS` or `MP_CHACO_RQI`



## Options Database Key

- ***-mat_partitioning_chaco_eigen_solver <method> -*** the eigensolver





## Note
The default is to use a Lanczos method. See Chaco documentation for details.


## See Also
 `MatPartitioningType`, `MatPartitioning`, `MATPARTITIONINGCHACO`, `MatPartitioningChacoSetEigenTol()`, `MatPartitioningChacoSetEigenNumber()`,
`MatPartitioningChacoGetEigenSolver()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/partition/impls/chaco/chaco.c.html#MatPartitioningChacoSetEigenSolver">src/mat/partition/impls/chaco/chaco.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/partition/impls/chaco/chaco.c.html#MatPartitioningChacoSetEigenSolver_Chaco">MatPartitioningChacoSetEigenSolver_Chaco in src/mat/partition/impls/chaco/chaco.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/partition/impls/chaco/chaco.c)


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