1: static char help[] = "Tests DMDAGetElements() and VecView() contour plotting for 2d DMDAs.\n\n";

  3: #include <petscdm.h>
  4: #include <petscdmda.h>

  6: int main(int argc, char **argv)
  7: {
  8:   PetscInt        M = 10, N = 8, ne, nc, i;
  9:   const PetscInt *e;
 10:   PetscBool       flg = PETSC_FALSE;
 11:   DM              da;
 12:   PetscViewer     viewer;
 13:   Vec             local, global;
 14:   PetscScalar     value;
 15:   DMBoundaryType  bx = DM_BOUNDARY_NONE, by = DM_BOUNDARY_NONE;
 16:   DMDAStencilType stype = DMDA_STENCIL_BOX;
 17:   PetscScalar    *lv;

 19:   PetscFunctionBeginUser;
 20:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
 21:   PetscCall(PetscViewerDrawOpen(PETSC_COMM_WORLD, NULL, "", 300, 0, 300, 300, &viewer));

 23:   /* Read options */
 24:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-M", &M, NULL));
 25:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-N", &N, NULL));
 26:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-star_stencil", &flg, NULL));
 27:   if (flg) stype = DMDA_STENCIL_STAR;

 29:   /* Create distributed array and get vectors */
 30:   PetscCall(DMDACreate2d(PETSC_COMM_WORLD, bx, by, stype, M, N, PETSC_DECIDE, PETSC_DECIDE, 1, 1, NULL, NULL, &da));
 31:   PetscCall(DMSetFromOptions(da));
 32:   PetscCall(DMSetUp(da));
 33:   PetscCall(DMCreateGlobalVector(da, &global));
 34:   PetscCall(DMCreateLocalVector(da, &local));

 36:   value = -3.0;
 37:   PetscCall(VecSet(global, value));
 38:   PetscCall(DMGlobalToLocalBegin(da, global, INSERT_VALUES, local));
 39:   PetscCall(DMGlobalToLocalEnd(da, global, INSERT_VALUES, local));

 41:   PetscCall(DMDASetElementType(da, DMDA_ELEMENT_P1));
 42:   PetscCall(DMDAGetElements(da, &ne, &nc, &e));
 43:   PetscCall(VecGetArray(local, &lv));
 44:   for (i = 0; i < ne; i++) {
 45:     PetscCall(PetscSynchronizedPrintf(PETSC_COMM_WORLD, "i %" PetscInt_FMT " e[3*i] %" PetscInt_FMT " %" PetscInt_FMT " %" PetscInt_FMT "\n", i, e[3 * i], e[3 * i + 1], e[3 * i + 2]));
 46:     lv[e[3 * i]] = i;
 47:   }
 48:   PetscCall(PetscSynchronizedFlush(PETSC_COMM_WORLD, stdout));
 49:   PetscCall(VecRestoreArray(local, &lv));
 50:   PetscCall(DMDARestoreElements(da, &ne, &nc, &e));

 52:   PetscCall(DMLocalToGlobalBegin(da, local, ADD_VALUES, global));
 53:   PetscCall(DMLocalToGlobalEnd(da, local, ADD_VALUES, global));

 55:   PetscCall(DMView(da, viewer));
 56:   PetscCall(VecView(global, viewer));

 58:   /* Free memory */
 59:   PetscCall(PetscViewerDestroy(&viewer));
 60:   PetscCall(VecDestroy(&local));
 61:   PetscCall(VecDestroy(&global));
 62:   PetscCall(DMDestroy(&da));
 63:   PetscCall(PetscFinalize());
 64:   return 0;
 65: }

 67: /*TEST

 69:    test:
 70:      requires: x

 72:    test:
 73:      suffix: 2
 74:      nsize: 2
 75:      requires: x

 77: TEST*/