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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
src/dm/impls/composite/pack.c
## Examples
src/snes/tutorials/ex28.c
src/snes/tutorials/ex73f90t.F90
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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/impls/composite/pack.c)
[Index of all DM routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)