# MatProductCreateWithMat
Setup a given matrix as a matrix product of other matrices 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatProductCreateWithMat(Mat A, Mat B, Mat C, Mat D)
```
Collective on Mat


## Input Parameters

- ***A -*** the first matrix
- ***B -*** the second matrix
- ***C -*** the third matrix (optional)
- ***D -*** the matrix which will be used to hold the product



## Output Parameters

- ***D -*** the product matrix



## Notes
Use `MatProductCreate()` if the matrix you wish computed (the D matrix) does not already exist

See `MatProductCreate()` for details on the usage of the MatProduct routines

Any product data currently attached to D will be cleared




## See Also
 `MatProductCreate()`, `MatProductClear()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matproduct.c.html#MatProductCreateWithMat">src/mat/interface/matproduct.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/interface/matproduct.c)


[Index of all Mat routines](index.md)  
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[Index of all manual pages](/docs/manualpages/singleindex.md)  
