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# DMCompositeGetGlobalISs
Gets the index sets for each composed object in a `DMCOMPOSITE` 
## Synopsis
```
#include "petscdmcomposite.h"  
PetscErrorCode DMCompositeGetGlobalISs(DM dm, IS *is[])
```
Collective


## Input Parameter

- ***dm -*** the `DMCOMPOSITE` object



## Output Parameter

- ***is -*** the array of index sets





## Notes
The is entries should be destroyed with `ISDestroy()`, the is array should be freed with `PetscFree()`

These could be used to extract a subset of vector entries for a "multi-physics" preconditioner

Use `DMCompositeGetLocalISs()` for index sets in the packed local numbering, and
`DMCompositeGetISLocalToGlobalMappings()` for to map local sub-`DM` (including ghost) indices to packed global
indices.


## Fortran Note
The output argument 'is' must be an allocated array of sufficient length, which can be learned using `DMCompositeGetNumberDM()`.


## See Also
 `DMCOMPOSITE`, `DM`, `DMDestroy()`, `DMCompositeAddDM()`, `DMCreateGlobalVector()`,
`DMCompositeGather()`, `DMCompositeCreate()`, `DMCompositeGetAccess()`, `DMCompositeScatter()`,
`DMCompositeGetLocalVectors()`, `DMCompositeRestoreLocalVectors()`, `DMCompositeGetEntries()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/composite/pack.c.html#DMCompositeGetGlobalISs">src/dm/impls/composite/pack.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex28.c.html">src/snes/tutorials/ex28.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex73f90t.F90.html">src/snes/tutorials/ex73f90t.F90</A><BR>


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


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