Actual source code: ex43.c
petsc-3.12.4 2020-02-04
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      1: static char help[] = "Demonstrates the DMLocalToLocal bug in PETSc 3.6.\n\n";

      3: /*
      4: Use the options
      5:      -da_grid_x <nx> - number of grid points in x direction, if M < 0
      6:      -da_grid_y <ny> - number of grid points in y direction, if N < 0
      7:      -da_processors_x <MX> number of processors in x directio
      8:      -da_processors_y <MY> number of processors in x direction

     10:   Contributed by Constantine Khroulev
     11: */

     13:  #include <petscdm.h>
     14:  #include <petscdmda.h>

     16: PetscErrorCode PrintVecWithGhosts(DM da, Vec v)
     17: {
     18:   PetscScalar    **p;
     19:   PetscInt       i, j;
     21:   MPI_Comm       com;
     22:   PetscMPIInt    rank;
     23:   DMDALocalInfo  info;

     25:   com = PetscObjectComm((PetscObject)da);
     26:   MPI_Comm_rank(com, &rank);
     27:   DMDAGetLocalInfo(da, &info);
     28:   PetscSynchronizedPrintf(com, "begin rank %d portion (with ghosts, %D x %D)\n",rank, info.gxm, info.gym);
     29:   DMDAVecGetArray(da, v, &p);
     30:   for (i = info.gxs; i < info.gxs + info.gxm; i++) {
     31:     for (j = info.gys; j < info.gys + info.gym; j++) {
     32:       PetscSynchronizedPrintf(com, "%g, ", (double) PetscRealPart(p[j][i]));
     33:     }
     34:     PetscSynchronizedPrintf(com, "\n");
     35:   }
     36:   DMDAVecRestoreArray(da, v, &p);
     37:   PetscSynchronizedPrintf(com, "end rank %d portion\n", rank);
     38:   PetscSynchronizedFlush(com, PETSC_STDOUT);
     39:   return 0;
     40: }

     42: /* Set a Vec v to value, but do not touch ghosts. */
     43: PetscErrorCode VecSetOwned(DM da, Vec v, PetscScalar value)
     44: {
     45:   PetscScalar    **p;
     46:   PetscInt         i, j, xs, xm, ys, ym;
     47:   PetscErrorCode   ierr;

     49:   DMDAGetCorners(da, &xs, &ys, 0, &xm, &ym, 0);
     50:   DMDAVecGetArray(da, v, &p);
     51:   for (i = xs; i < xs + xm; i++) {
     52:     for (j = ys; j < ys + ym; j++) {
     53:       p[j][i] = value;
     54:     }
     55:   }
     56:   DMDAVecRestoreArray(da, v, &p);
     57:   return 0;
     58: }

     60: int main(int argc, char **argv)
     61: {
     62:   PetscInt         M = 4, N = 3;
     63:   PetscErrorCode   ierr;
     64:   DM               da;
     65:   Vec              local;
     66:   PetscScalar      value = 0.0;
     67:   DMBoundaryType   bx    = DM_BOUNDARY_PERIODIC, by = DM_BOUNDARY_PERIODIC;
     68:   DMDAStencilType  stype = DMDA_STENCIL_BOX;

     70:   PetscInitialize(&argc, &argv, (char*)0, help);if (ierr) return ierr;
     71:   DMDACreate2d(PETSC_COMM_WORLD,bx,by,stype,M,N,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da);
     72:   DMSetFromOptions(da);
     73:   DMSetUp(da);
     74:   DMCreateLocalVector(da, &local);

     76:   VecSet(local, value);
     77:   PetscPrintf(PETSC_COMM_WORLD, "\nAfter setting all values to %d:\n", (int)PetscRealPart(value));
     78:   PrintVecWithGhosts(da, local);
     79:   PetscPrintf(PETSC_COMM_WORLD, "done\n");

     81:   value += 1.0;
     82:   /* set values owned by a process, leaving ghosts alone */
     83:   VecSetOwned(da, local, value);

     85:   /* print after re-setting interior values again */
     86:   PetscPrintf(PETSC_COMM_WORLD, "\nAfter setting interior values to %d:\n", (int)PetscRealPart(value));
     87:   PrintVecWithGhosts(da, local);
     88:   PetscPrintf(PETSC_COMM_WORLD, "done\n");

     90:   /* communicate ghosts */
     91:   DMLocalToLocalBegin(da, local, INSERT_VALUES, local);
     92:   DMLocalToLocalEnd(da, local, INSERT_VALUES, local);

     94:   /* print again */
     95:   PetscPrintf(PETSC_COMM_WORLD, "\nAfter local-to-local communication:\n");
     96:   PrintVecWithGhosts(da, local);
     97:   PetscPrintf(PETSC_COMM_WORLD, "done\n");

     99:   /* Free memory */
    100:   VecDestroy(&local);
    101:   DMDestroy(&da);
    102:   PetscFinalize();
    103:   return ierr;
    104: }

    107: /*TEST

    109:    test:
    110:       nsize: 2

    112: TEST*/