xref: /petsc/src/dm/tests/ex43.c (revision 030f984af8d8bb4c203755d35bded3c05b3d83ce)
1 static char help[] = "Demonstrates the DMLocalToLocal bug in PETSc 3.6.\n\n";
2 
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
9 
10   Contributed by Constantine Khroulev
11 */
12 
13 #include <petscdm.h>
14 #include <petscdmda.h>
15 
16 PetscErrorCode PrintVecWithGhosts(DM da, Vec v)
17 {
18   PetscScalar    **p;
19   PetscInt       i, j;
20   PetscErrorCode ierr;
21   MPI_Comm       com;
22   PetscMPIInt    rank;
23   DMDALocalInfo  info;
24 
25   com = PetscObjectComm((PetscObject)da);
26   ierr = MPI_Comm_rank(com, &rank);CHKERRMPI(ierr);
27   ierr = DMDAGetLocalInfo(da, &info);CHKERRQ(ierr);
28   ierr = PetscSynchronizedPrintf(com, "begin rank %d portion (with ghosts, %D x %D)\n",rank, info.gxm, info.gym);CHKERRQ(ierr);
29   ierr = DMDAVecGetArray(da, v, &p);CHKERRQ(ierr);
30   for (i = info.gxs; i < info.gxs + info.gxm; i++) {
31     for (j = info.gys; j < info.gys + info.gym; j++) {
32       ierr = PetscSynchronizedPrintf(com, "%g, ", (double) PetscRealPart(p[j][i]));CHKERRQ(ierr);
33     }
34     ierr = PetscSynchronizedPrintf(com, "\n");CHKERRQ(ierr);
35   }
36   ierr = DMDAVecRestoreArray(da, v, &p);CHKERRQ(ierr);
37   ierr = PetscSynchronizedPrintf(com, "end rank %d portion\n", rank);CHKERRQ(ierr);
38   ierr = PetscSynchronizedFlush(com, PETSC_STDOUT);CHKERRQ(ierr);
39   return 0;
40 }
41 
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;
48 
49   ierr = DMDAGetCorners(da, &xs, &ys, 0, &xm, &ym, 0);CHKERRQ(ierr);
50   ierr = DMDAVecGetArray(da, v, &p);CHKERRQ(ierr);
51   for (i = xs; i < xs + xm; i++) {
52     for (j = ys; j < ys + ym; j++) {
53       p[j][i] = value;
54     }
55   }
56   ierr = DMDAVecRestoreArray(da, v, &p);CHKERRQ(ierr);
57   return 0;
58 }
59 
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;
69 
70   ierr = PetscInitialize(&argc, &argv, (char*)0, help);if (ierr) return ierr;
71   ierr = DMDACreate2d(PETSC_COMM_WORLD,bx,by,stype,M,N,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da);CHKERRQ(ierr);
72   ierr = DMSetFromOptions(da);CHKERRQ(ierr);
73   ierr = DMSetUp(da);CHKERRQ(ierr);
74   ierr = DMCreateLocalVector(da, &local);CHKERRQ(ierr);
75 
76   ierr  = VecSet(local, value);CHKERRQ(ierr);
77   ierr = PetscPrintf(PETSC_COMM_WORLD, "\nAfter setting all values to %d:\n", (int)PetscRealPart(value));CHKERRQ(ierr);
78   ierr = PrintVecWithGhosts(da, local);CHKERRQ(ierr);
79   ierr = PetscPrintf(PETSC_COMM_WORLD, "done\n");CHKERRQ(ierr);
80 
81   value += 1.0;
82   /* set values owned by a process, leaving ghosts alone */
83   ierr = VecSetOwned(da, local, value);CHKERRQ(ierr);
84 
85   /* print after re-setting interior values again */
86   ierr = PetscPrintf(PETSC_COMM_WORLD, "\nAfter setting interior values to %d:\n", (int)PetscRealPart(value));CHKERRQ(ierr);
87   ierr = PrintVecWithGhosts(da, local);CHKERRQ(ierr);
88   ierr = PetscPrintf(PETSC_COMM_WORLD, "done\n");CHKERRQ(ierr);
89 
90   /* communicate ghosts */
91   ierr  = DMLocalToLocalBegin(da, local, INSERT_VALUES, local);CHKERRQ(ierr);
92   ierr  = DMLocalToLocalEnd(da, local, INSERT_VALUES, local);CHKERRQ(ierr);
93 
94   /* print again */
95   ierr = PetscPrintf(PETSC_COMM_WORLD, "\nAfter local-to-local communication:\n");CHKERRQ(ierr);
96   ierr = PrintVecWithGhosts(da, local);CHKERRQ(ierr);
97   ierr = PetscPrintf(PETSC_COMM_WORLD, "done\n");CHKERRQ(ierr);
98 
99   /* Free memory */
100   ierr = VecDestroy(&local);CHKERRQ(ierr);
101   ierr = DMDestroy(&da);CHKERRQ(ierr);
102   ierr = PetscFinalize();
103   return ierr;
104 }
105 
106 /*TEST
107 
108    test:
109       nsize: 2
110 
111 TEST*/
112