# PCGASMGetSubKSP
Gets the local `KSP` contexts for all subdomains on this MPI rank. 
## Synopsis
```
#include "petscpc.h" 
PetscErrorCode PCGASMGetSubKSP(PC pc, PetscInt *n_local, PetscInt *first_local, KSP *ksp[])
```
Collective iff first_local is requested


## Input Parameter

- ***pc -*** the preconditioner context



## Output Parameters

- ***n_local -*** the number of blocks on this MPI rank or NULL
- ***first_local -*** the global number of the first block on this rank or NULL,
all ranks must request or all must pass NULL
- ***ksp -*** the array of `KSP` contexts



## Note
After `PCGASMGetSubKSP()` the array of `KSP`es is not to be freed

Currently for some matrix implementations only 1 block per MPI rank
is supported.

You must call `KSPSetUp()` before calling `PCGASMGetSubKSP()`.




## See Also
 `PCGASM`, `PCGASMSetSubdomains()`, `PCGASMSetOverlap()`,
`PCGASMCreateSubdomains2D()`,

## Level
advanced

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex62.c.html">src/ksp/ksp/tutorials/ex62.c.html</A><BR>

## Implementations

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


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


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