petsc-3.14.5 2021-03-03
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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 on PC

### Input Parameters

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

| rscale | - the scaling

### Notes

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

PCMGSetInterpolation(), PCMGSetRestriction(), PCMGGetRScale(), PCMGSetInjection()

### Level

advanced

### Location

src/ksp/pc/impls/mg/mgfunc.c
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages