:orphan:
# VecAXPY
Computes `y = alpha x + y`. 
## Synopsis
```
#include "petscvec.h"   
PetscErrorCode VecAXPY(Vec y, PetscScalar alpha, Vec x)
```
Logically Collective


## Input Parameters

- ***alpha -*** the scalar
- ***x -*** vector scale by `alpha`
- ***y -*** vector accumulated into



## Output Parameter

- ***y -*** output vector





## Notes
This routine is optimized for alpha of 0.0, otherwise it calls the BLAS routine
```none
    VecAXPY(y,alpha,x)                   y = alpha x           +      y
    VecAYPX(y,beta,x)                    y =       x           + beta y
    VecAXPBY(y,alpha,beta,x)             y = alpha x           + beta y
    VecWAXPY(w,alpha,x,y)                w = alpha x           +      y
    VecAXPBYPCZ(w,alpha,beta,gamma,x,y)  z = alpha x           + beta y + gamma z
    VecMAXPY(y,nv,alpha[],x[])           y = sum alpha[i] x[i] +      y
```



## See Also
 [](ch_vectors), `Vec`, `VecAYPX()`, `VecMAXPY()`, `VecWAXPY()`, `VecAXPBYPCZ()`, `VecAXPBY()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/interface/rvector.c.html#VecAXPY">src/vec/vec/interface/rvector.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex1.c.html">src/dm/impls/stag/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex2.c.html">src/dm/impls/stag/tutorials/ex2.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex3.c.html">src/dm/impls/stag/tutorials/ex3.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/tutorials/ex10.c.html">src/dm/tutorials/ex10.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/tutorials/ex15.c.html">src/dm/tutorials/ex15.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/bench_kspsolve.c.html">src/ksp/ksp/tutorials/bench_kspsolve.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex1.c.html">src/ksp/ksp/tutorials/ex1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex11.c.html">src/ksp/ksp/tutorials/ex11.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex11f.F90.html">src/ksp/ksp/tutorials/ex11f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex12.c.html">src/ksp/ksp/tutorials/ex12.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex15.c.html">src/ksp/ksp/tutorials/ex15.c</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/impls/nest/vecnest.c.html#VecAXPY_Nest">VecAXPY_Nest in src/vec/vec/impls/nest/vecnest.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/impls/seq/bvec1.c.html#VecAXPY_Seq">VecAXPY_Seq in src/vec/vec/impls/seq/bvec1.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/impls/seq/kokkos/veckok.kokkos.cxx.html#VecAXPY_SeqKokkos">VecAXPY_SeqKokkos in src/vec/vec/impls/seq/kokkos/veckok.kokkos.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/impls/seq/seqviennacl/vecviennacl.cxx.html#VecAXPY_SeqViennaCL">VecAXPY_SeqViennaCL in src/vec/vec/impls/seq/seqviennacl/vecviennacl.cxx</A><BR>


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