:orphan:
# PetscSFGetMultiSF
gets the inner `PetscSF` implementing gathers and scatters
## Synopsis
```
#include "petscsf.h"
PetscErrorCode PetscSFGetMultiSF(PetscSF sf, PetscSF *multi)
```
Collective
## Input Parameter
- ***sf -*** star forest that may contain roots with 0 or with more than 1 vertex
## Output Parameter
- ***multi -*** star forest with split roots, such that each root has degree exactly 1
## Note
In most cases, users should use `PetscSFGatherBegin()` and `PetscSFScatterBegin()` instead of manipulating multi
directly. Since multi satisfies the stronger condition that each entry in the global space has exactly one incoming
edge, it is a candidate for future optimization that might involve its removal.
## See Also
`PetscSF`, `PetscSFSetGraph()`, `PetscSFGatherBegin()`, `PetscSFScatterBegin()`, `PetscSFComputeMultiRootOriginalNumbering()`
## Level
developer
## Location
src/vec/is/sf/interface/sf.c
## Examples
src/vec/is/sf/tutorials/ex1.c
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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/is/sf/interface/sf.c)
[Index of all PetscSF routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)