xref: /petsc/src/dm/tutorials/ex5.c (revision b122ec5aa1bd4469eb4e0673542fb7de3f411254)
1 
2 static char help[] = "Tests DMDAGetElements() and VecView() contour plotting for 2d DMDAs.\n\n";
3 
4 #include <petscdm.h>
5 #include <petscdmda.h>
6 #include <petscdraw.h>
7 
8 int main(int argc,char **argv)
9 {
10   PetscInt         M = 10,N = 8,ne,nc,i;
11   const PetscInt   *e;
12   PetscBool        flg = PETSC_FALSE;
13   DM               da;
14   PetscViewer      viewer;
15   Vec              local,global;
16   PetscScalar      value;
17   DMBoundaryType   bx    = DM_BOUNDARY_NONE,by = DM_BOUNDARY_NONE;
18   DMDAStencilType  stype = DMDA_STENCIL_BOX;
19   PetscScalar      *lv;
20 
21   CHKERRQ(PetscInitialize(&argc,&argv,(char*)0,help));
22   CHKERRQ(PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"",300,0,300,300,&viewer));
23 
24   /* Read options */
25   CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-M",&M,NULL));
26   CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-N",&N,NULL));
27   CHKERRQ(PetscOptionsGetBool(NULL,NULL,"-star_stencil",&flg,NULL));
28   if (flg) stype = DMDA_STENCIL_STAR;
29 
30   /* Create distributed array and get vectors */
31   CHKERRQ(DMDACreate2d(PETSC_COMM_WORLD,bx,by,stype,M,N,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da));
32   CHKERRQ(DMSetFromOptions(da));
33   CHKERRQ(DMSetUp(da));
34   CHKERRQ(DMCreateGlobalVector(da,&global));
35   CHKERRQ(DMCreateLocalVector(da,&local));
36 
37   value = -3.0;
38   CHKERRQ(VecSet(global,value));
39   CHKERRQ(DMGlobalToLocalBegin(da,global,INSERT_VALUES,local));
40   CHKERRQ(DMGlobalToLocalEnd(da,global,INSERT_VALUES,local));
41 
42   CHKERRQ(DMDASetElementType(da,DMDA_ELEMENT_P1));
43   CHKERRQ(DMDAGetElements(da,&ne,&nc,&e));
44   CHKERRQ(VecGetArray(local,&lv));
45   for (i=0; i<ne; i++) {
46     CHKERRQ(PetscSynchronizedPrintf(PETSC_COMM_WORLD,"i %D e[3*i] %D %D %D\n",i,e[3*i],e[3*i+1],e[3*i+2]));
47     lv[e[3*i]] = i;
48   }
49   CHKERRQ(PetscSynchronizedFlush(PETSC_COMM_WORLD,stdout));
50   CHKERRQ(VecRestoreArray(local,&lv));
51   CHKERRQ(DMDARestoreElements(da,&ne,&nc,&e));
52 
53   CHKERRQ(DMLocalToGlobalBegin(da,local,ADD_VALUES,global));
54   CHKERRQ(DMLocalToGlobalEnd(da,local,ADD_VALUES,global));
55 
56   CHKERRQ(DMView(da,viewer));
57   CHKERRQ(VecView(global,viewer));
58 
59   /* Free memory */
60   CHKERRQ(PetscViewerDestroy(&viewer));
61   CHKERRQ(VecDestroy(&local));
62   CHKERRQ(VecDestroy(&global));
63   CHKERRQ(DMDestroy(&da));
64   CHKERRQ(PetscFinalize());
65   return 0;
66 }
67 
68 /*TEST
69 
70    test:
71      requires: x
72 
73    test:
74      suffix: 2
75      nsize: 2
76      requires: x
77 
78 TEST*/
79