petsc-3.14.5 2021-03-03
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# 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

src/vec/is/is/interface/index.c
Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages