xref: /petsc/src/dm/tutorials/ex1.c (revision 327415f76d85372a4417cf1aaa14db707d4d6c04)
1c4762a1bSJed Brown 
2c4762a1bSJed Brown static char help[] = "Tests VecView() contour plotting for 2d DMDAs.\n\n";
3c4762a1bSJed Brown 
4c4762a1bSJed Brown /*
5c4762a1bSJed Brown   MATLAB must be installed to configure PETSc to have MATLAB engine.
6c4762a1bSJed Brown Unless you have specific important reasons for using the MATLAB engine, we do not
7c4762a1bSJed Brown recommend it. If you want to use MATLAB for visualization and maybe a little post processing
8c4762a1bSJed Brown then you can use the socket viewer and send the data to MATLAB via that.
9c4762a1bSJed Brown 
10c4762a1bSJed Brown   VecView() on DMDA vectors first puts the Vec elements into global natural ordering before printing (or plotting)
11c4762a1bSJed Brown them. In 2d 5 by 2 DMDA this means the numbering is
12c4762a1bSJed Brown 
13c4762a1bSJed Brown      5  6   7   8   9
14c4762a1bSJed Brown      0  1   2   3   4
15c4762a1bSJed Brown 
16c4762a1bSJed Brown Now the default split across 2 processors with the DM  is (by rank)
17c4762a1bSJed Brown 
18c4762a1bSJed Brown     0  0   0  1   1
19c4762a1bSJed Brown     0  0   0  1   1
20c4762a1bSJed Brown 
21c4762a1bSJed Brown So the global PETSc ordering is
22c4762a1bSJed Brown 
23c4762a1bSJed Brown     3  4  5   8  9
24c4762a1bSJed Brown     0  1  2   6  7
25c4762a1bSJed Brown 
26c4762a1bSJed Brown Use the options
27c4762a1bSJed Brown      -da_grid_x <nx> - number of grid points in x direction, if M < 0
28c4762a1bSJed Brown      -da_grid_y <ny> - number of grid points in y direction, if N < 0
29c4762a1bSJed Brown      -da_processors_x <MX> number of processors in x directio
30c4762a1bSJed Brown      -da_processors_y <MY> number of processors in x direction
31c4762a1bSJed Brown */
32c4762a1bSJed Brown 
33c4762a1bSJed Brown #include <petscdm.h>
34c4762a1bSJed Brown #include <petscdmda.h>
35c4762a1bSJed Brown 
36c4762a1bSJed Brown int main(int argc,char **argv)
37c4762a1bSJed Brown {
38c4762a1bSJed Brown   PetscMPIInt      rank;
39c4762a1bSJed Brown   PetscInt         M = 10,N = 8;
40c4762a1bSJed Brown   PetscBool        flg = PETSC_FALSE;
41c4762a1bSJed Brown   DM               da;
42c4762a1bSJed Brown   PetscViewer      viewer;
43c4762a1bSJed Brown   Vec              local,global;
44c4762a1bSJed Brown   PetscScalar      value;
45c4762a1bSJed Brown   DMBoundaryType   bx    = DM_BOUNDARY_NONE,by = DM_BOUNDARY_NONE;
46c4762a1bSJed Brown   DMDAStencilType  stype = DMDA_STENCIL_BOX;
47c4762a1bSJed Brown #if defined(PETSC_HAVE_MATLAB_ENGINE)
48c4762a1bSJed Brown   PetscViewer      mviewer;
49c4762a1bSJed Brown   PetscMPIInt      size;
50c4762a1bSJed Brown #endif
51c4762a1bSJed Brown 
52*327415f7SBarry Smith   PetscFunctionBeginUser;
539566063dSJacob Faibussowitsch   PetscCall(PetscInitialize(&argc,&argv,(char*)0,help));
549566063dSJacob Faibussowitsch   PetscCall(PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"",300,0,300,300,&viewer));
55c4762a1bSJed Brown #if defined(PETSC_HAVE_MATLAB_ENGINE)
569566063dSJacob Faibussowitsch   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
57c4762a1bSJed Brown   if (size == 1) {
589566063dSJacob Faibussowitsch     PetscCall(PetscViewerMatlabOpen(PETSC_COMM_WORLD,"tmp.mat",FILE_MODE_WRITE,&mviewer));
59c4762a1bSJed Brown   }
60c4762a1bSJed Brown #endif
61c4762a1bSJed Brown 
629566063dSJacob Faibussowitsch   PetscCall(PetscOptionsGetBool(NULL,NULL,"-star_stencil",&flg,NULL));
63c4762a1bSJed Brown   if (flg) stype = DMDA_STENCIL_STAR;
64c4762a1bSJed Brown 
65c4762a1bSJed Brown   /* Create distributed array and get vectors */
669566063dSJacob Faibussowitsch   PetscCall(DMDACreate2d(PETSC_COMM_WORLD,bx,by,stype,M,N,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da));
679566063dSJacob Faibussowitsch   PetscCall(DMSetFromOptions(da));
689566063dSJacob Faibussowitsch   PetscCall(DMSetUp(da));
699566063dSJacob Faibussowitsch   PetscCall(DMCreateGlobalVector(da,&global));
709566063dSJacob Faibussowitsch   PetscCall(DMCreateLocalVector(da,&local));
71c4762a1bSJed Brown 
72c4762a1bSJed Brown   value = -3.0;
739566063dSJacob Faibussowitsch   PetscCall(VecSet(global,value));
749566063dSJacob Faibussowitsch   PetscCall(DMGlobalToLocalBegin(da,global,INSERT_VALUES,local));
759566063dSJacob Faibussowitsch   PetscCall(DMGlobalToLocalEnd(da,global,INSERT_VALUES,local));
76c4762a1bSJed Brown 
779566063dSJacob Faibussowitsch   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));
78c4762a1bSJed Brown   value = rank+1;
799566063dSJacob Faibussowitsch   PetscCall(VecScale(local,value));
809566063dSJacob Faibussowitsch   PetscCall(DMLocalToGlobalBegin(da,local,ADD_VALUES,global));
819566063dSJacob Faibussowitsch   PetscCall(DMLocalToGlobalEnd(da,local,ADD_VALUES,global));
82c4762a1bSJed Brown 
83c4762a1bSJed Brown   flg  = PETSC_FALSE;
849566063dSJacob Faibussowitsch   PetscCall(PetscOptionsGetBool(NULL,NULL, "-view_global", &flg,NULL));
85c4762a1bSJed Brown   if (flg) { /* view global vector in natural ordering */
869566063dSJacob Faibussowitsch     PetscCall(VecView(global,PETSC_VIEWER_STDOUT_WORLD));
87c4762a1bSJed Brown   }
889566063dSJacob Faibussowitsch   PetscCall(DMView(da,viewer));
899566063dSJacob Faibussowitsch   PetscCall(VecView(global,viewer));
90c4762a1bSJed Brown #if defined(PETSC_HAVE_MATLAB_ENGINE)
91c4762a1bSJed Brown   if (size == 1) {
929566063dSJacob Faibussowitsch     PetscCall(DMView(da,mviewer));
939566063dSJacob Faibussowitsch     PetscCall(VecView(global,mviewer));
94c4762a1bSJed Brown   }
95c4762a1bSJed Brown #endif
96c4762a1bSJed Brown 
97c4762a1bSJed Brown   /* Free memory */
98c4762a1bSJed Brown #if defined(PETSC_HAVE_MATLAB_ENGINE)
99c4762a1bSJed Brown   if (size == 1) {
1009566063dSJacob Faibussowitsch     PetscCall(PetscViewerDestroy(&mviewer));
101c4762a1bSJed Brown   }
102c4762a1bSJed Brown #endif
1039566063dSJacob Faibussowitsch   PetscCall(PetscViewerDestroy(&viewer));
1049566063dSJacob Faibussowitsch   PetscCall(VecDestroy(&local));
1059566063dSJacob Faibussowitsch   PetscCall(VecDestroy(&global));
1069566063dSJacob Faibussowitsch   PetscCall(DMDestroy(&da));
1079566063dSJacob Faibussowitsch   PetscCall(PetscFinalize());
108b122ec5aSJacob Faibussowitsch   return 0;
109c4762a1bSJed Brown }
110c4762a1bSJed Brown 
111c4762a1bSJed Brown /*TEST
112c4762a1bSJed Brown 
113c4762a1bSJed Brown    test:
114c4762a1bSJed Brown       requires: x
115c4762a1bSJed Brown       nsize: 2
116c4762a1bSJed Brown       args: -nox
117c4762a1bSJed Brown 
118c4762a1bSJed Brown TEST*/
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