[petsc-users] DMPlexCreateFromCellList and hybrid meshes

[Matthew Knepley]

On Fri, Oct 25, 2013 at 7:23 AM, Cedric Doucet <cedric.doucet at inria.fr>wrote:

> Hello,
>
> I've noticed that DMPlexCreateFromCellList assumes that cells have the
> same number of vertices (numcorners argument).
> What should be done when one wants to create a DMPlex from a mesh
> containing different types of cells?
> Does one have to create several DMPlex structures and merge them?
> Does one have to create a unique DMPlex by hand?
>

The code is very short:

  ierr = DMPlexSetChart(dm, 0, numCells+numVertices);CHKERRQ(ierr);
  for (c = 0; c < numCells; ++c) {
    ierr = DMPlexSetConeSize(dm, c, numCorners);CHKERRQ(ierr);
  }
  ierr = DMSetUp(dm);CHKERRQ(ierr);
  ierr = DMGetWorkArray(dm, numCorners, PETSC_INT, &cone);CHKERRQ(ierr);
  for (c = 0; c < numCells; ++c) {
    for (p = 0; p < numCorners; ++p) {
      cone[p] = cells[c*numCorners+p]+numCells;
    }
    ierr = DMPlexSetCone(dm, c, cone);CHKERRQ(ierr);
  }
  ierr = DMRestoreWorkArray(dm, numCorners, PETSC_INT, &cone);CHKERRQ(ierr);
  ierr = DMPlexSymmetrize(dm);CHKERRQ(ierr);
  ierr = DMPlexStratify(dm);CHKERRQ(ierr);

This code is all in plexcreate.c. If you want different cells, you can
change numCorners for each cell.
I could make a convenience form if necessary.

   Matt


>
> Thank you very much for your help.
>
> Cédric
>
>
>
>


-- 
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
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