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

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

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

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

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

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

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

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

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

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

 59:   /* Free memory */
 60:   PetscCall(PetscViewerDestroy(&viewer));
 61:   PetscCall(VecDestroy(&local));
 62:   PetscCall(VecDestroy(&global));
 63:   PetscCall(DMDestroy(&da));
 64:   PetscCall(PetscFinalize());
 65:   return 0;
 66: }

 68: /*TEST

 70:    test:
 71:      requires: x

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

 78: TEST*/