[petsc-dev] getting data out of a PetscFE simulation

[Geoffrey Irving]

On Tue, Jan 28, 2014 at 8:24 PM, Jed Brown <jed at jedbrown.org> wrote:
> Matthew Knepley <knepley at gmail.com> writes:
>
>> On Tue, Jan 28, 2014 at 9:41 PM, Jed Brown <jed at jedbrown.org> wrote:
>>
>>> Matthew Knepley <knepley at gmail.com> writes:
>>> > In ex62:
>>> >
>>> >   if (user.runType == RUN_FULL) {
>>> >     PetscViewer viewer;
>>> >     Vec         uLocal;
>>> >     const char *name;
>>> >
>>> >     ierr = PetscViewerCreate(PETSC_COMM_WORLD, &viewer);CHKERRQ(ierr);
>>> >     ierr = PetscViewerSetType(viewer, PETSCVIEWERVTK);CHKERRQ(ierr);
>>> >     ierr = PetscViewerSetFormat(viewer,
>>> > PETSC_VIEWER_ASCII_VTK);CHKERRQ(ierr);
>>> >     ierr = PetscViewerFileSetName(viewer, "ex62_sol.vtk");CHKERRQ(ierr);
>>>
>>> Please don't do this.  Just set the type to PETSCVIEWERVTK, set the file
>>> name to some *.vtu; the VTK viewer will infer output format from
>>> extension and write the VTU XML format with binary-appended data in a
>>> fairly fast and memory-scalable way.  Then
>>>
>>>   VecView(u,viewer);
>>
>> I think Jed is wrong here. You need to be using local vectors since
>> they have BC and constraints in them. Please explain how your VTU
>> format will magically put them in.
>
> We made this work when I threw a temper tantrum while we were writing TS
> ex11.c (late 2012).
>
> PetscErrorCode VecView_Plex(Vec v, PetscViewer viewer)
> {
>   DM             dm;
>   PetscBool      isvtk;
>   PetscErrorCode ierr;
>
>   PetscFunctionBegin;
>   ierr = VecGetDM(v, &dm);CHKERRQ(ierr);
>   if (!dm) SETERRQ(PetscObjectComm((PetscObject)v), PETSC_ERR_ARG_WRONG, "Vector not generated from a DM");
>   ierr = PetscObjectTypeCompare((PetscObject) viewer, PETSCVIEWERVTK, &isvtk);CHKERRQ(ierr);
>   if (isvtk) {
>     Vec         locv;
>     const char *name;
>
>     ierr = DMGetLocalVector(dm, &locv);CHKERRQ(ierr);
>     ierr = PetscObjectGetName((PetscObject) v, &name);CHKERRQ(ierr);
>     ierr = PetscObjectSetName((PetscObject) locv, name);CHKERRQ(ierr);
>     ierr = DMGlobalToLocalBegin(dm, v, INSERT_VALUES, locv);CHKERRQ(ierr);
>     ierr = DMGlobalToLocalEnd(dm, v, INSERT_VALUES, locv);CHKERRQ(ierr);
>     ierr = VecView_Plex_Local(locv, viewer);CHKERRQ(ierr);
>     ierr = DMRestoreLocalVector(dm, &locv);CHKERRQ(ierr);

Which of those lines adds the correct boundary condition values?

Geoffrey