[petsc-users] Output cell data related to DMDA

Denis Davydov davydden at gmail.com
Fri Dec 18 02:29:05 CST 2020

Hi Matt,

By global vector you mean one created with

VecCreateMPI(..., nel, PETSC_DETERMINE,...)

? If so, that gives segfault (even with 1 MPI process) in user write function, which is just 


which clearly indicates that I misunderstand your comment.

Would you please clarify what PETSc expect as a “global” vector in case of cell-based quantities as opposed to unknowns/fields associated with the DMDA discretization?


> Am 17.12.2020 um 18:58 schrieb Matthew Knepley <knepley at gmail.com>:
>> On Thu, Dec 17, 2020 at 12:18 PM Denis Davydov <davydden at gmail.com> wrote:
>> Dear all,
>> I would like to output cell data (eg conductivity coefficient) in VTK for DMDA setup.
>> Given that I know how many elements/cells are owned locally, I hoped that PetscViewerVTKAddField with PETSC_VTK_CELL_FIELD would do the job.
>> However I am not sure whether provided vector should be fully distributed (no ghosts)? If not, can I get the required ghosts from DMDA created with DMDACreate3D ?
> I believe that it outputs global vectors, meaning that there are no ghosts.
>   Thanks,
>      Matt
>> Ps. I saw just one relevant discussion on the mailing list.
>> Sincerely,
>> Denis
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> https://www.cse.buffalo.edu/~knepley/
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