petsc-3.12.4 2020-02-04
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# ISCreateSubIS

Create a sub index set from a global index set selecting some components.

### Synopsis

    #include "petscis.h"
    PetscErrorCode ISCreateSubIS(IS is,IS comps,IS *subis)

Collective on IS

### Input Parmeters

| is | - the index set
| comps | - which components we will extract from is

### Output Parameters

subis -the new sub index set

### Example usage

### We have an index set (is) living on 3 processes with the following values

| 4 9 0 | 2 6 7 | 10 11 1| and another index set (comps) used to indicate which components of is we want to take, | 7 5 | 1 2 | 0 4|

### The output index set (subis) should look like

| 11 7 | 9 0 | 4 6|

### See Also

VecGetSubVector(), MatCreateSubMatrix()

### Level

intermediate

### 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