# PCGAMGSetReuseInterpolation
Reuse prolongation when rebuilding a `PCGAMG` algebraic multigrid preconditioner 
## Synopsis
```
#include "petscpc.h" 
#include "petscksp.h" 
PetscErrorCode PCGAMGSetReuseInterpolation(PC pc, PetscBool n)
```
Collective


## Input Parameters

- ***pc -*** the preconditioner context
- ***n -*** `PETSC_TRUE` or `PETSC_FALSE`



## Options Database Key

- ***-pc_gamg_reuse_interpolation <true,false> -*** reuse the previous interpolation





## Note
May negatively affect the convergence rate of the method on new matrices if the matrix entries change a great deal, but allows
rebuilding the preconditioner quicker.


## See Also
 `PCGAMG`

## Level
intermediate

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

## Implementations

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


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


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