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# ISGetBlockSize
Returns the number of elements in a block. 
## Synopsis
```
#include "petscis.h" 
PetscErrorCode ISGetBlockSize(IS is, PetscInt *size)
```
Not Collective


## Input Parameter

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



## Output Parameter

- ***size -*** the number of elements in a block





## Note
See `ISSetBlockSize()`


## See Also
 `IS`, `ISBlockGetSize()`, `ISGetSize()`, `ISCreateBlock()`, `ISSetBlockSize()`

## Level
intermediate

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/is/tutorials/ex3.c.html">src/vec/is/is/tutorials/ex3.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/is/tutorials/ex3f90.F90.html">src/vec/is/is/tutorials/ex3f90.F90</A><BR>


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[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)