# PETSC_VIEWER_SOCKET_
Creates a socket viewer shared by all processors in a communicator. 
## Synopsis
```
PetscViewer PETSC_VIEWER_SOCKET_(MPI_Comm comm)
```
Collective


## Input Parameter

- ***comm -*** the MPI communicator to share the  `PETSCVIEWERSOCKET` `PetscViewer`





## Options Database Keys
For use with the default `PETSC_VIEWER_SOCKET_WORLD` or if
NULL is passed for machine or `PETSC_DEFAULT` is passed for port
```none
-viewer_socket_machine <machine>
```
```none
-viewer_socket_port <port>
```


## Environmental variables

- ***`PETSC_VIEWER_SOCKET_PORT` -*** portnumber
- ***`PETSC_VIEWER_SOCKET_MACHINE` -*** machine name



## Notes
Unlike almost all other PETSc routines, `PETSC_VIEWER_SOCKET_()` does not return
an error code, it returns NULL if it fails. The  `PETSCVIEWERSOCKET`  `PetscViewer` is usually used in the form
```none
XXXView(XXX object,PETSC_VIEWER_SOCKET_(comm));
```

Currently the only socket client available is MATLAB. See
src/dm/tests/ex12.c and ex12.m for an example of usage.

Connects to a waiting socket and stays connected until `PetscViewerDestroy()` is called.

Use this for communicating with an interactive MATLAB session, see `PETSC_VIEWER_MATLAB_()` for writing output to a
.mat file. Use `PetscMatlabEngineCreate()` or `PETSC_MATLAB_ENGINE_()`, `PETSC_MATLAB_ENGINE_SELF`, or `PETSC_MATLAB_ENGINE_WORLD`
for communicating with a MATLAB Engine


## See Also
 `PETSCVIEWERMATLAB`, `PETSCVIEWERSOCKET`, `PETSC_VIEWER_SOCKET_WORLD`, `PETSC_VIEWER_SOCKET_SELF`, `PetscViewerSocketOpen()`, `PetscViewerCreate()`,
`PetscViewerSocketSetConnection()`, `PetscViewerDestroy()`, `PETSC_VIEWER_SOCKET_()`, `PetscViewerBinaryWrite()`, `PetscViewerBinaryRead()`,
`PetscViewerBinaryWriteStringArray()`, `PetscViewerBinaryGetDescriptor()`, `PETSC_VIEWER_MATLAB_()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/classes/viewer/impls/socket/send.c.html#PETSC_VIEWER_SOCKET_">src/sys/classes/viewer/impls/socket/send.c</A>


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/classes/viewer/impls/socket/send.c)


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