1: static char help[] = "Test degenerate near null space";

  3: #include <petscdmplex.h>
  4: #include <petscsnes.h>
  5: #include <petscds.h>
  6: #include <petscbag.h>
  7: #include <petscconvest.h>

  9: static PetscErrorCode CreateMesh(MPI_Comm comm, DM *dm)
 10: {
 11:   PetscFunctionBeginUser;
 12:   PetscCall(DMCreate(comm, dm));
 13:   PetscCall(DMSetType(*dm, DMPLEX));
 14:   PetscCall(DMSetFromOptions(*dm));
 15:   PetscCall(DMViewFromOptions(*dm, NULL, "-dm_view"));
 16:   PetscFunctionReturn(PETSC_SUCCESS);
 17: }

 19: static PetscErrorCode SetupBoundaries(DM dm)
 20: {
 21:   DMLabel  label;
 22:   PetscInt id;
 23:   PetscInt dim;

 25:   PetscFunctionBeginUser;
 26:   PetscCall(DMGetCoordinateDim(dm, &dim));
 27:   PetscCall(DMGetLabel(dm, "Face Sets", &label));
 28:   PetscCheck(label, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_INCOMP, "Must have face sets label");

 30:   if (dim == 2) {
 31:     PetscInt cmp, cmps_y[] = {0, 1};

 33:     cmp = 0;
 34:     id  = 4;
 35:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "left", label, 1, &id, 0, 1, &cmp, NULL, NULL, NULL, NULL));
 36:     cmp = 0;
 37:     id  = 2;
 38:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "right", label, 1, &id, 0, 1, &cmp, NULL, NULL, NULL, NULL));
 39:     id = 1;
 40:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "bottom", label, 1, &id, 0, 2, cmps_y, NULL, NULL, NULL, NULL));
 41:   } else if (dim == 3) {
 42:     PetscInt cmps_xy[] = {0, 1};
 43:     PetscInt cmps_z[]  = {0, 1, 2};

 45:     id = 6;
 46:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "left", label, 1, &id, 0, 2, cmps_xy, NULL, NULL, NULL, NULL));
 47:     id = 5;
 48:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "right", label, 1, &id, 0, 2, cmps_xy, NULL, NULL, NULL, NULL));
 49:     id = 2;
 50:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "bottom", label, 1, &id, 0, 3, cmps_z, NULL, NULL, NULL, NULL));
 51:     id = 3;
 52:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "front", label, 1, &id, 0, 2, cmps_xy, NULL, NULL, NULL, NULL));
 53:     id = 4;
 54:     PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "back", label, 1, &id, 0, 2, cmps_xy, NULL, NULL, NULL, NULL));
 55:   }
 56:   PetscFunctionReturn(PETSC_SUCCESS);
 57: }

 59: PetscErrorCode SetupFE(DM dm, const char name[])
 60: {
 61:   PetscFE        fe;
 62:   char           prefix[PETSC_MAX_PATH_LEN];
 63:   DMPolytopeType ct;
 64:   PetscInt       dim, cStart;

 66:   PetscFunctionBegin;
 67:   /* Create finite element */
 68:   PetscCall(DMGetDimension(dm, &dim));
 69:   PetscCall(DMPlexGetHeightStratum(dm, 0, &cStart, NULL));
 70:   PetscCall(DMPlexGetCellType(dm, cStart, &ct));
 71:   PetscCall(PetscSNPrintf(prefix, PETSC_MAX_PATH_LEN, "%s_", name));
 72:   PetscCall(PetscFECreateByCell(PETSC_COMM_SELF, dim, dim, ct, name ? prefix : NULL, -1, &fe));
 73:   PetscCall(PetscObjectSetName((PetscObject)fe, name));
 74:   /* Set discretization and boundary conditions for each mesh */
 75:   PetscCall(DMSetField(dm, 0, NULL, (PetscObject)fe));
 76:   PetscCall(DMCreateDS(dm));
 77:   PetscCall(SetupBoundaries(dm));
 78:   PetscCall(PetscFEDestroy(&fe));
 79:   PetscFunctionReturn(PETSC_SUCCESS);
 80: }

 82: PetscErrorCode MakeNullSpaceRigidBody(DM dm)
 83: {
 84:   Mat          A;
 85:   MatNullSpace null_space;

 87:   PetscFunctionBegin;
 88:   /* Create null space and set onto matrix */
 89:   PetscCall(DMCreateMatrix(dm, &A));
 90:   PetscCall(DMPlexCreateRigidBody(dm, 0, &null_space));
 91:   PetscCall(MatSetNearNullSpace(A, null_space));
 92:   PetscCall(MatNullSpaceView(null_space, PETSC_VIEWER_STDOUT_WORLD));
 93:   PetscCall(MatNullSpaceDestroy(&null_space));
 94:   PetscCall(MatDestroy(&A));
 95:   PetscFunctionReturn(PETSC_SUCCESS);
 96: }

 98: int main(int argc, char **argv)
 99: {
100:   DM dm;

102:   PetscFunctionBeginUser;
103:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
104:   PetscCall(CreateMesh(PETSC_COMM_WORLD, &dm));
105:   PetscCall(SetupFE(dm, "displacement"));
106:   PetscCall(MakeNullSpaceRigidBody(dm));
107:   PetscCall(DMDestroy(&dm));
108:   PetscCall(PetscFinalize());
109:   return 0;
110: }

112: /*TEST

114:   test:
115:     suffix: 3d_q1
116:     args: -dm_plex_box_faces 1,1,2 -dm_plex_simplex 0 -dm_plex_dim 3 -displacement_petscspace_degree 1

118:   test:
119:     suffix: 3d_q2
120:     args: -dm_plex_box_faces 1,1,2 -dm_plex_simplex 0 -dm_plex_dim 3 -displacement_petscspace_degree 2

122:   test:
123:     suffix: 2d_q1
124:     args: -dm_plex_box_faces 1,2 -dm_plex_simplex 0 -dm_plex_dim 2 -displacement_petscspace_degree 1

126:   test:
127:     suffix: 2d_q2
128:     args: -dm_plex_box_faces 1,2 -dm_plex_simplex 0 -dm_plex_dim 2 -displacement_petscspace_degree 2

130: TEST*/