[petsc-users] distribute and cells mapping.

[Olivier Bonnefon]

On 08/23/2013 04:42 PM, Matthew Knepley wrote:
> On Fri, Aug 23, 2013 at 9:35 AM, Olivier Bonnefon 
> <olivier.bonnefon at avignon.inra.fr 
> <mailto:olivier.bonnefon at avignon.inra.fr>> wrote:
>
>     Hello,
>
>     Thanks for your answers, I'm now able to import and distribute a mesh:
>
>
> You might simplify this to
>
> if (rank) {obNbCells = 0; obNbVertex = 0;}
> ierr = 
> DMPlexCreateFromCellList(comm,dim,obNbCells,obNbVertex,3,0,obCells,2,obVertex,dm);CHKERRQ(ierr);
>
>     if (!rank){
>             ierr =
>     DMPlexCreateFromCellList(comm,dim,obNbCells,obNbVertex,3,0,obCells,2,obVertex,dm);CHKERRQ(ierr);
>              for (i=0;i<obNbBound;i++){
>                ierr =DMPlexSetLabelValue(*dm, "marker",
>     obBoundary[i]+obNbCells, 1);CHKERRQ(ierr);
>              }
>     }else {
>               ierr =
>     DMPlexCreateFromCellList(comm,dim,0,0,3,0,obCells,2,obVertex,dm);CHKERRQ(ierr);
>     }
>
>     ierr = DMPlexDistribute(*dm, partitioner, 0,
>     &distributedMesh);CHKERRQ(ierr);
>     if (distributedMesh) {
>           ierr = DMDestroy(dm);CHKERRQ(ierr);
>           *dm  = distributedMesh;
>     }
>
>     Is it possible to known the resulting partition ? ie, What is the
>     mapping between the initial cell number and the local cell (used
>     in DMPlexComputeResidualFEM)?
>     I need this to write an efficient implementation of the FEM struct
>     functions f0 and g0, space depending.
>
>
> Yes, but I really do not think you want to do things that way. I am 
> assuming you want different material models or something
> in different places. The way I envision that is using a DMLabel to 
> mark up parts of the domain. All labels are automatically
> distributed with the mesh. Is that what you want?
Hello,

It is exactly what I need: I'm mobilized a landscape, and the parameters 
of the model depend of the type of crop. Therefore, I have created a 
label for each type of crop and I have labeled each triangle with the 
corresponding label:

  for (i=0;i<obNbCells;i++){
      if (labelCells[i]==1){
         ierr =DMPlexSetLabelValue(*dm, "marker1", i, 1);CHKERRQ(ierr);
      }else{
         ierr =DMPlexSetLabelValue(*dm, "marker2", i, 1);CHKERRQ(ierr);
      }
  }

So, I'm able to mark the triangles, but I'm not able to get this label 
in the plugin "fem.f0Funcs" and "fem.g0Funcs": These plugins are called 
by looping on the triangles in the function "FEMIntegrateResidualBatch", 
but the dm is not available, so I can't use the functions 
DMPlexGetLabel, DMLabelGetStratumSize and DMLabelGetStratumIS. What is 
the good way to get the labels in the user plugins of the fem struct ?


Thanks a lot for your help.

Olivier B
>
>   Thanks,
>
>      Matt
>
>     Regards,
>
>     Olivier B
>
>     -- 
>     Olivier Bonnefon
>     INRA PACA-Avignon, Unité BioSP
>     Tel: +33 (0)4 32 72 21 58 <tel:%2B33%20%280%294%2032%2072%2021%2058>
>
>
>
>
> -- 
> 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


-- 
Olivier Bonnefon
INRA PACA-Avignon, Unité BioSP
Tel: +33 (0)4 32 72 21 58

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