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# VecStrideGather
Gathers a single component from a multi-component vector into another vector. 
## Synopsis
```
#include "petscvec.h" 
PetscErrorCode VecStrideGather(Vec v, PetscInt start, Vec s, InsertMode addv)
```
Collective


## Input Parameters

- ***v -*** the vector
- ***start -*** starting point of the subvector (defined by a stride)
- ***addv -*** one of `ADD_VALUES`, `INSERT_VALUES`, `MAX_VALUES`



## Output Parameter

- ***s -*** the location where the subvector is stored





## Notes
One must call `VecSetBlockSize()` before this routine to set the stride
information, or use a vector created from a multicomponent `DMDA`.

If x is the array representing the vector x then this gathers
the array (x[start],x[start+stride],x[start+2*stride], ....)

The parallel layout of the vector and the subvector must be the same;
i.e., nlocal of v = stride*(nlocal of s)

Not optimized; could be easily


## See Also
 `Vec`, `VecStrideNorm()`, `VecStrideScatter()`, `VecStrideMin()`, `VecStrideMax()`, `VecStrideGatherAll()`,
`VecStrideScatterAll()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/vinv.c.html#VecStrideGather">src/vec/vec/utils/vinv.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex12.c.html">src/vec/vec/tutorials/ex12.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex12f.F90.html">src/vec/vec/tutorials/ex12f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/tutorials/ex16.c.html">src/vec/vec/tutorials/ex16.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/vec/utils/vinv.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)