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# VecCreateShared
Creates a parallel vector that uses shared memory. 
## Synopsis
```
#include "petscvec.h"   
PetscErrorCode VecCreateShared(MPI_Comm comm, PetscInt n, PetscInt N, Vec *v)
```
Collective


## Input Parameters

- ***comm -*** the MPI communicator to use
- ***n -*** local vector length (or `PETSC_DECIDE` to have calculated if `N` is given)
- ***N -*** global vector length (or `PETSC_DECIDE` to have calculated if `n` is given)



## Output Parameter

- ***vv -*** the vector





## Notes
Currently `VecCreateShared()` is available only on the SGI; otherwise,
this routine is the same as `VecCreateMPI()`.

Use `VecDuplicate()` or `VecDuplicateVecs()` to form additional vectors of the
same type as an existing vector.


## See Also
 [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreate()`, `VecCreateMPI()`, `VecDuplicate()`, `VecDuplicateVecs()`,
`VecCreateGhost()`, `VecCreateMPIWithArray()`, `VecCreateGhostWithArray()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/impls/shared/shvec.c.html#VecCreateShared">src/vec/vec/impls/shared/shvec.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex1.c.html">src/vec/vec/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex11.c.html">src/vec/vec/tutorials/ex11.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex11f.F90.html">src/vec/vec/tutorials/ex11f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex11f90.F90.html">src/vec/vec/tutorials/ex11f90.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex13.c.html">src/vec/vec/tutorials/ex13.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex1f.F90.html">src/vec/vec/tutorials/ex1f.F90</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/vec/impls/shared/shvec.c)


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