1: static char help[] = "Define a simple field over the mesh\n\n";

  3: #include <petscdmplex.h>

  5: int main(int argc, char **argv)
  6: {
  7:   DM             dm;
  8:   Vec            u;
  9:   PetscSection   section;
 10:   PetscViewer    viewer;
 11:   PetscInt       dim, numFields, numBC, i;
 12:   PetscInt       numComp[3];
 13:   PetscInt       numDof[12];
 14:   PetscInt       bcField[1];
 15:   IS             bcPointIS[1];

 18:   PetscInitialize(&argc, &argv, NULL,help);if (ierr) return ierr;
 19:   /* Create a mesh */
 20:   DMCreate(PETSC_COMM_WORLD, &dm);
 21:   DMSetType(dm, DMPLEX);
 22:   DMSetFromOptions(dm);
 23:   DMViewFromOptions(dm, NULL, "-dm_view");
 24:   DMGetDimension(dm, &dim);
 25:   /* Create a scalar field u, a vector field v, and a surface vector field w */
 26:   numFields  = 3;
 27:   numComp[0] = 1;
 28:   numComp[1] = dim;
 29:   numComp[2] = dim-1;
 30:   for (i = 0; i < numFields*(dim+1); ++i) numDof[i] = 0;
 31:   /* Let u be defined on vertices */
 32:   numDof[0*(dim+1)+0]     = 1;
 33:   /* Let v be defined on cells */
 34:   numDof[1*(dim+1)+dim]   = dim;
 35:   /* Let w be defined on faces */
 36:   numDof[2*(dim+1)+dim-1] = dim-1;
 37:   /* Setup boundary conditions */
 38:   numBC = 1;
 39:   /* Prescribe a Dirichlet condition on u on the boundary
 40:        Label "marker" is made by the mesh creation routine */
 41:   bcField[0] = 0;
 42:   DMGetStratumIS(dm, "marker", 1, &bcPointIS[0]);
 43:   /* Create a PetscSection with this data layout */
 44:   DMSetNumFields(dm, numFields);
 45:   DMPlexCreateSection(dm, NULL, numComp, numDof, numBC, bcField, NULL, bcPointIS, NULL, &section);
 46:   ISDestroy(&bcPointIS[0]);
 47:   /* Name the Field variables */
 48:   PetscSectionSetFieldName(section, 0, "u");
 49:   PetscSectionSetFieldName(section, 1, "v");
 50:   PetscSectionSetFieldName(section, 2, "w");
 51:   PetscSectionView(section, PETSC_VIEWER_STDOUT_WORLD);
 52:   /* Tell the DM to use this data layout */
 53:   DMSetLocalSection(dm, section);
 54:   /* Create a Vec with this layout and view it */
 55:   DMGetGlobalVector(dm, &u);
 56:   PetscViewerCreate(PETSC_COMM_WORLD, &viewer);
 57:   PetscViewerSetType(viewer, PETSCVIEWERVTK);
 58:   PetscViewerFileSetName(viewer, "sol.vtu");
 59:   VecView(u, viewer);
 60:   PetscViewerDestroy(&viewer);
 61:   DMRestoreGlobalVector(dm, &u);
 62:   /* Cleanup */
 63:   PetscSectionDestroy(&section);
 64:   DMDestroy(&dm);
 65:   PetscFinalize();
 66:   return ierr;
 67: }

 69: /*TEST

 71:   test:
 72:     suffix: 0
 73:     requires: triangle
 74:     args: -info :~sys,mat
 75:   test:
 76:     suffix: 1
 77:     requires: ctetgen
 78:     args: -dm_plex_dim 3 -info :~sys,mat

 80: TEST*/