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# MatMatSolve
Solves A X = B, given a factored matrix. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatMatSolve(Mat A, Mat B, Mat X)
```
Neighbor-wise Collective


## Input Parameters

- ***A -*** the factored matrix
- ***B -*** the right-hand-side matrix `MATDENSE` (or sparse `MATAIJ`-- when using MUMPS)



## Output Parameter

- ***X -*** the result matrix (dense matrix)





## Note
If `B` is a `MATDENSE` matrix then one can call `MatMatSolve`(A,B,B) except with `MATSOLVERMKL_CPARDISO`;
otherwise, `B` and `X` cannot be the same.


## See Also
 [](ch_matrices), `Mat`, [Matrix Factorization](sec_matfactor), `MatGetFactor()`, `MatSolve()`, `MatMatSolveTranspose()`, `MatLUFactor()`, `MatCholeskyFactor()`

## Level
developer

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex74.c.html">src/ksp/ksp/tutorials/ex74.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex77.c.html">src/ksp/ksp/tutorials/ex77.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex77f.F90.html">src/ksp/ksp/tutorials/ex77f.F90</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mumps/mumps.c.html#MatMatSolve_MUMPS">MatMatSolve_MUMPS in src/mat/impls/aij/mpi/mumps/mumps.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/strumpack/strumpack.c.html#MatMatSolve_STRUMPACK">MatMatSolve_STRUMPACK in src/mat/impls/aij/mpi/strumpack/strumpack.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/aijfact.c.html#MatMatSolve_SeqAIJ">MatMatSolve_SeqAIJ in src/mat/impls/aij/seq/aijfact.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/spqr/aijspqr.c.html#MatMatSolve_SPQR">MatMatSolve_SPQR in src/mat/impls/aij/seq/spqr/aijspqr.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/superlu/superlu.c.html#MatMatSolve_SuperLU">MatMatSolve_SuperLU in src/mat/impls/aij/seq/superlu/superlu.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/elemental/matelem.cxx.html#MatMatSolve_Elemental">MatMatSolve_Elemental in src/mat/impls/elemental/matelem.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/seq/cholmod/sbaijcholmod.c.html#MatMatSolve_CHOLMOD">MatMatSolve_CHOLMOD in src/mat/impls/sbaij/seq/cholmod/sbaijcholmod.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/scalapack/matscalapack.c.html#MatMatSolve_ScaLAPACK">MatMatSolve_ScaLAPACK in src/mat/impls/scalapack/matscalapack.c</A><BR>


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


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