Actual source code: ex51.c


  2: static char help[] = "Tests DMDAGlobalToNaturalAllCreate() using contour plotting for 2d DMDAs.\n\n";

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

  8: int main(int argc, char **argv)
  9: {
 10:   PetscInt        i, j, M = 10, N = 8, m = PETSC_DECIDE, n = PETSC_DECIDE;
 11:   PetscMPIInt     rank;
 12:   PetscBool       flg = PETSC_FALSE;
 13:   DM              da;
 14:   PetscViewer     viewer;
 15:   Vec             localall, global;
 16:   PetscScalar     value, *vlocal;
 17:   DMBoundaryType  bx = DM_BOUNDARY_NONE, by = DM_BOUNDARY_NONE;
 18:   DMDAStencilType stype = DMDA_STENCIL_BOX;
 19:   VecScatter      tolocalall, fromlocalall;
 20:   PetscInt        start, end;

 23:   PetscInitialize(&argc, &argv, (char *)0, help);
 24:   PetscViewerDrawOpen(PETSC_COMM_WORLD, 0, "", 300, 0, 300, 300, &viewer);

 26:   /* Read options */
 27:   PetscOptionsGetInt(NULL, NULL, "-M", &M, NULL);
 28:   PetscOptionsGetInt(NULL, NULL, "-N", &N, NULL);
 29:   PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL);
 30:   PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL);
 31:   PetscOptionsGetBool(NULL, NULL, "-star_stencil", &flg, NULL);
 32:   if (flg) stype = DMDA_STENCIL_STAR;

 34:   /* Create distributed array and get vectors */
 35:   DMDACreate2d(PETSC_COMM_WORLD, bx, by, stype, M, N, m, n, 1, 1, NULL, NULL, &da);
 36:   DMSetFromOptions(da);
 37:   DMSetUp(da);

 39:   DMCreateGlobalVector(da, &global);
 40:   VecCreateSeq(PETSC_COMM_SELF, M * N, &localall);

 42:   MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
 43:   VecGetOwnershipRange(global, &start, &end);
 44:   for (i = start; i < end; i++) {
 45:     value = 5.0 * rank;
 46:     VecSetValues(global, 1, &i, &value, INSERT_VALUES);
 47:   }
 48:   VecView(global, viewer);

 50:   /*
 51:      Create Scatter from global DMDA parallel vector to local vector that
 52:    contains all entries
 53:   */
 54:   DMDAGlobalToNaturalAllCreate(da, &tolocalall);
 55:   DMDANaturalAllToGlobalCreate(da, &fromlocalall);

 57:   VecScatterBegin(tolocalall, global, localall, INSERT_VALUES, SCATTER_FORWARD);
 58:   VecScatterEnd(tolocalall, global, localall, INSERT_VALUES, SCATTER_FORWARD);

 60:   VecGetArray(localall, &vlocal);
 61:   for (j = 0; j < N; j++) {
 62:     for (i = 0; i < M; i++) *vlocal++ += i + j * M;
 63:   }
 64:   VecRestoreArray(localall, &vlocal);

 66:   /* scatter back to global vector */
 67:   VecScatterBegin(fromlocalall, localall, global, INSERT_VALUES, SCATTER_FORWARD);
 68:   VecScatterEnd(fromlocalall, localall, global, INSERT_VALUES, SCATTER_FORWARD);

 70:   VecView(global, viewer);

 72:   /* Free memory */
 73:   VecScatterDestroy(&tolocalall);
 74:   VecScatterDestroy(&fromlocalall);
 75:   PetscViewerDestroy(&viewer);
 76:   VecDestroy(&localall);
 77:   VecDestroy(&global);
 78:   DMDestroy(&da);
 79:   PetscFinalize();
 80:   return 0;
 81: }

 83: /*TEST

 85:    build:
 86:      requires: !complex

 88:    test:
 89:       nsize: 3

 91: TEST*/