:orphan:
# VecDotBegin
Starts a split phase dot product computation. 
## Synopsis
```
#include "petscvec.h"    
PetscErrorCode VecDotBegin(Vec x, Vec y, PetscScalar *result)
```

## Input Parameters

- ***x -*** the first vector
- ***y -*** the second vector
- ***result -*** where the result will go (can be NULL)





## Notes
Each call to `VecDotBegin()` should be paired with a call to `VecDotEnd()`.


## See Also
 `VecDotEnd()`, `VecNormBegin()`, `VecNormEnd()`, `VecNorm()`, `VecDot()`, `VecMDot()`,
`VecTDotBegin()`, `VecTDotEnd()`, `PetscCommSplitReductionBegin()`

## Level
advanced

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


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