:orphan:
# ISSetPermutation
Informs the index set that it is a permutation. 
## Synopsis
```
#include "petscis.h" 
PetscErrorCode ISSetPermutation(IS is)
```
Logically Collective


## Input Parameter

- ***is -*** the index set





## Notes
`is` will be considered a permutation permanently, even if indices have been changes (for example, with
`ISGeneralSetIndices()`).  It's a good idea to only set this property if `is` will not change in the future.

To clear this property, use `ISClearInfoCache()`.

The debug version of the libraries (./configure --with-debugging=1) checks if the
index set is actually a permutation. The optimized version just believes you.


## See Also
 `IS`, `ISPermutation()`, `ISSetInfo()`, `ISClearInfoCache().`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/is/interface/index.c.html#ISSetPermutation">src/vec/is/is/interface/index.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/is/is/interface/index.c)


[Index of all IS routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)