# PCCompositeSpecialSetAlpha
Sets alpha for the special composite preconditioner, `PC_COMPOSITE_SPECIAL`, for alphaI + R + S 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode PCCompositeSpecialSetAlpha(PC pc, PetscScalar alpha)
```
Logically Collective


## Input Parameters

- ***pc -*** the preconditioner context
- ***alpha -*** scale on identity





## See Also
 `PCCOMPOSITE`, `PC_COMPOSITE_ADDITIVE`, `PC_COMPOSITE_MULTIPLICATIVE`, `PC_COMPOSITE_SPECIAL`, `PCCompositeType`,
`PCCompositeSetType()`, `PCCompositeGetType()`

## Level
Developer

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

## Implementations

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


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


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