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# PCMGSetRScale
Sets the pointwise scaling for the restriction operator from level l to l-1. 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode PCMGSetRScale(PC pc, PetscInt l, Vec rscale)
```
Logically Collective


## Input Parameters

- ***pc -*** the multigrid context
- ***l -*** the level (0 is coarsest) to supply [Do not supply 0]


- ***rscale -*** the scaling





## Note
When evaluating a function on a coarse level one does not want to do F(R * x) one does F(rscale * R * x) where rscale is 1 over the row sums of R.
It is preferable to use `PCMGSetInjection()` to control moving primal vectors.


## See Also
 `PCMG`, `PCMGSetInterpolation()`, `PCMGSetRestriction()`, `PCMGGetRScale()`, `PCMGSetInjection()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/mg/mgfunc.c.html#PCMGSetRScale">src/ksp/pc/impls/mg/mgfunc.c</A>


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


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