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# PetscViewerMatlabOpen
Opens a Matlab .mat file for output
## Synopsis
```
PetscErrorCode PetscViewerMatlabOpen(MPI_Comm comm, const char name[], PetscFileMode type, PetscViewer *binv)
```
Collective
## Input Parameters
- ***comm -*** MPI communicator
- ***name -*** name of file
- ***type -*** type of file
```none
FILE_MODE_WRITE - create new file for MATLAB output
FILE_MODE_READ - open existing file for MATLAB input
FILE_MODE_WRITE - open existing file for MATLAB output
```
## Output Parameter
- ***binv -*** PetscViewer for MATLAB output to use with the specified file
## Notes
This `PetscViewer` should be destroyed with `PetscViewerDestroy()`.
For writing files it only opens the file on processor 0 in the communicator.
This only saves `Vec`s it cannot be used to save `Mat`s. We recommend using the `PETSCVIEWERBINARY` to save objects to be loaded into MATLAB
instead of this routine.
PETSc must be configured with the option `--with-matlab` for this functionality
## See Also
`PETSCVIEWERMATLAB`, `PetscViewerASCIIOpen()`, `PetscViewerPushFormat()`, `PetscViewerDestroy()`, `PETSCVIEWERBINARY`, `PetscViewerBinaryOpen()`
`VecView()`, `MatView()`, `VecLoad()`, `MatLoad()`
## Level
beginner
## Location
src/sys/classes/viewer/impls/matlab/vmatlab.c
## Examples
src/dm/tutorials/ex1.c
src/snes/tutorials/ex30.c
---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/classes/viewer/impls/matlab/vmatlab.c)
[Index of all Viewer routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)