petsc-3.10.5 2019-03-28
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# PetscOptionsGetViewer

Gets a viewer appropriate for the type indicated by the user

### Synopsis

    #include "petscviewer.h"
    PetscErrorCode  PetscOptionsGetViewer(MPI_Comm comm,const char pre[],const char name[],PetscViewer *viewer,PetscViewerFormat *format,PetscBool  *set)

Collective on MPI_Comm

### Input Parameters

| comm | - the communicator to own the viewer
| pre | - the string to prepend to the name or NULL
| name | - the option one is seeking

### Output Parameter

| viewer | - the viewer, pass NULL if not needed
| format | - the PetscViewerFormat requested by the user, pass NULL if not needed
| set | - PETSC_TRUE if found, else PETSC_FALSE

### Notes

If no value is provided ascii:stdout is used

          ascii[:[filename][:[format][:append]]]    defaults to stdout - format can be one of ascii_info, ascii_info_detail, or ascii_matlab,

for example ascii::ascii_info prints just the information about the object not all details unless :append is given filename opens in write mode, overwriting what was already there

          binary[:[filename][:[format][:append]]]   defaults to the file binaryoutput

          draw[:drawtype[:filename]]                for example, draw:tikz, draw:tikz:figure.tex  or draw:x

          socket[:port]                             defaults to the standard output port

          saws[:communicatorname]                    publishes object to the Scientific Application Webserver (SAWs)

Use PetscViewerDestroy() after using the viewer, otherwise a memory leak will occur

You can control whether calls to this function create a viewer (or return early with *set of PETSC_FALSE) with PetscOptionsPushGetViewerOff. This is useful if calling many small subsolves, in which case XXXViewFromOptions can take an appreciable fraction of the runtime.

If PETSc is configured with --with-viewfromoptions=0 this function always returns with *set of PETSC_FALSE

### See Also

PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool() PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(), PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(), PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(), PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(), PetscOptionsFList(), PetscOptionsEList(), PetscOptionsPushGetViewerOff(), PetscOptionsPopGetViewerOff(), PetscOptionsGetViewerOff()

### Level

intermediate

### Location

src/sys/classes/viewer/interface/viewreg.c

### Examples

src/sys/classes/viewer/examples/tutorials/ex2.c.html
src/sys/examples/tutorials/ex15.c.html
src/vec/vec/utils/tagger/examples/tutorials/ex1.c.html
src/dm/impls/forest/examples/tutorials/ex1.c.html
src/snes/examples/tutorials/ex56.c.html
Index of all Viewer routines
Table of Contents for all manual pages
Index of all manual pages