[petsc-users] Creating a 3D dmplex mesh with cell list and distributing it

[Swarnava Ghosh]

Hi Matthew,

I added DMView(pCgdft->dmplex,PETSC_VIEWER_STDOUT_WORLD); before and after
distribution, and I get the following:

dmplex before distribution
DM Object: 3 MPI processes
  type: plex
DM_0x84000004_0 in 3 dimensions:
  0-cells: 7 7 7
  1-cells: 17 17 17
  2-cells: 17 17 17
  3-cells: 6 6 6
Labels:
  depth: 4 strata with value/size (0 (7), 1 (17), 2 (17), 3 (6))
dmplex after distribution
DM Object: Parallel Mesh 3 MPI processes
  type: plex
Parallel Mesh in 3 dimensions:
  0-cells: 7 7 7
  1-cells: 17 17 17
  2-cells: 17 17 17
  3-cells: 6 6 6
Labels:
  depth: 4 strata with value/size (0 (7), 1 (17), 2 (17), 3 (6))

Thanks,
SG

On Wed, Aug 14, 2019 at 6:48 PM Matthew Knepley <knepley at gmail.com> wrote:

> DMView() the mesh before and after distribution, so we can see what we
> have.
>
>   Thanks,
>
>      Matt
>
> On Wed, Aug 14, 2019 at 5:30 PM Swarnava Ghosh via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Hi PETSc team and users,
>>
>> I am trying to create a 3D dmplex mesh using DMPlexCreateFromCellList,
>> then distribute it, and find out the coordinates of the vertices owned by
>> each process.
>> My cell list is as follows:
>> numCells: 6
>> numVertices: 7
>> numCorners: 4
>> cells:
>> 0
>> 3
>> 2
>> 1
>> 4
>> 0
>> 2
>> 1
>> 6
>> 4
>> 2
>> 1
>> 3
>> 6
>> 2
>> 1
>> 5
>> 4
>> 6
>> 1
>> 3
>> 5
>> 6
>> 1
>> vertexCoords:
>> -6.043000
>> -5.233392
>> -4.924000
>> -3.021500
>> 0.000000
>> -4.924000
>> -3.021500
>> -3.488928
>> 0.000000
>> -6.043000
>> 1.744464
>> 0.000000
>> 0.000000
>> -5.233392
>> -4.924000
>> 3.021500
>> 0.000000
>> -4.924000
>> 3.021500
>> -3.488928
>> 0.000000
>>
>> After reading this information, I do
>>  ierr=
>> DMPlexCreateFromCellList(PETSC_COMM_WORLD,3,pCgdft->numCellsESP,pCgdft->NESP,pCgdft->numCornersESP,interpolate,pCgdft->cellsESP,3,pCgdft->vertexCoordsESP,&pCgdft->dmplex);
>>
>> ierr = DMPlexDistribute(pCgdft->dmplex,0,&pCgdft->dmplexSF,
>> &distributedMesh);CHKERRQ(ierr);
>>
>>    if (distributedMesh) {
>>      printf("mesh is distributed \n");
>>    ierr = DMDestroy(&pCgdft->dmplex);CHKERRQ(ierr);
>>      pCgdft->dmplex  = distributedMesh;
>>   }
>>
>>  DMGetCoordinates(pCgdft->dmplex,&VC);
>>  VecView(VC,PETSC_VIEWER_STDOUT_WORLD);
>>
>> On running this with 3 mpi processes, From VecView, I see that all the
>> processes own all the vertices.  Why is the dmplex not being distributed?
>>
>> The VecView is :
>> Process [0]
>> -6.043
>> -5.23339
>> -4.924
>> -3.0215
>> 0.
>> -4.924
>> -3.0215
>> -3.48893
>> 0.
>> -6.043
>> 1.74446
>> 0.
>> 0.
>> -5.23339
>> -4.924
>> 3.0215
>> 0.
>> -4.924
>> 3.0215
>> -3.48893
>> 0.
>> Process [1]
>> -6.043
>> -5.23339
>> -4.924
>> -3.0215
>> 0.
>> -4.924
>> -3.0215
>> -3.48893
>> 0.
>> -6.043
>> 1.74446
>> 0.
>> 0.
>> -5.23339
>> -4.924
>> 3.0215
>> 0.
>> -4.924
>> 3.0215
>> -3.48893
>> 0.
>> Process [2]
>> -6.043
>> -5.23339
>> -4.924
>> -3.0215
>> 0.
>> -4.924
>> -3.0215
>> -3.48893
>> 0.
>> -6.043
>> 1.74446
>> 0.
>> 0.
>> -5.23339
>> -4.924
>> 3.0215
>> 0.
>> -4.924
>> 3.0215
>> -3.48893
>> 0.
>>
>> Thanks,
>> SG
>>
>>
>
> --
> 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/
> <http://www.cse.buffalo.edu/~knepley/>
>
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