# ISSetInfo
Set known information about an index set. 
## Synopsis
```
#include "petscis.h" 
PetscErrorCode ISSetInfo(IS is, ISInfo info, ISInfoType type, PetscBool permanent, PetscBool flg)
```
Logically Collective on IS if type is IS_GLOBAL


## Input Parameters

- ***is -*** the index set
- ***info -*** describing a property of the index set, one of those listed below,
- ***type -*** IS_LOCAL if the information describes the local portion of the index set,
IS_GLOBAL if it describes the whole index set
- ***permanent -*** PETSC_TRUE if it is known that the property will persist through changes to the index set, PETSC_FALSE otherwise
If the user sets a property as permanently known, it will bypass computation of that property
- ***flg -*** set the described property as true (PETSC_TRUE) or false (PETSC_FALSE)



## Info Describing IS Structure

- ***IS_SORTED -*** the [local part of the] index set is sorted in ascending order
- ***IS_UNIQUE -*** each entry in the [local part of the] index set is unique
- ***IS_PERMUTATION -*** the [local part of the] index set is a permutation of the integers {0, 1, ..., N-1}, where N is the size of the [local part of the] index set
- ***IS_INTERVAL -*** the [local part of the] index set is equal to a contiguous range of integers {f, f + 1, ..., f + N-1}
- ***IS_IDENTITY -*** the [local part of the] index set is equal to the integers {0, 1, ..., N-1}



## Notes
If type is IS_GLOBAL, all processes that share the index set must pass the same value in flg

It is possible to set a property with ISSetInfo() that contradicts what would be previously computed with ISGetInfo()




## See Also
 `ISInfo`, `ISInfoType`, `IS`


## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/is/interface/index.c.html#ISSetInfo">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](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
