# KSPChebyshevEstEigSetUseNoisy
use a noisy right hand side in order to do the estimate instead of the given right hand side 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode KSPChebyshevEstEigSetUseNoisy(KSP ksp, PetscBool use)
```
Logically Collective


## Input Parameters

- ***ksp -*** linear solver context
- ***use -*** `PETSC_TRUE` to use noisy



## Options Database Key

- ***-ksp_chebyshev_esteig_noisy <true,false> -*** Use noisy right hand side for estimate



## Note
This allegedly works better for multigrid smoothers




## See Also
 [](chapter_ksp), `KSPCHEBYSHEV`, `KSPChebyshevEstEigSet()`, `KSPChebyshevEstEigGetKSP()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/cheby/cheby.c.html#KSPChebyshevEstEigSetUseNoisy">src/ksp/ksp/impls/cheby/cheby.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/cheby/cheby.c.html#KSPChebyshevEstEigSetUseNoisy_Chebyshev">KSPChebyshevEstEigSetUseNoisy_Chebyshev in src/ksp/ksp/impls/cheby/cheby.c</A><BR>


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


[Index of all KSP routines](index.md)  
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