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

  4: /*
  5:   MATLAB must be installed to configure PETSc to have MATLAB engine.
  6: Unless you have specific important reasons for using the MATLAB engine, we do not
  7: recommend it. If you want to use MATLAB for visualization and maybe a little post processing
  8: then you can use the socket viewer and send the data to MATLAB via that.

 10:   VecView() on DMDA vectors first puts the Vec elements into global natural ordering before printing (or plotting)
 11: them. In 2d 5 by 2 DMDA this means the numbering is

 13:      5  6   7   8   9
 14:      0  1   2   3   4

 16: Now the default split across 2 processors with the DM  is (by rank)

 18:     0  0   0  1   1
 19:     0  0   0  1   1

 21: So the global PETSc ordering is

 23:     3  4  5   8  9
 24:     0  1  2   6  7

 26: Use the options
 27:      -da_grid_x <nx> - number of grid points in x direction, if M < 0
 28:      -da_grid_y <ny> - number of grid points in y direction, if N < 0
 29:      -da_processors_x <MX> number of processors in x directio
 30:      -da_processors_y <MY> number of processors in x direction
 31: */

 33: #include <petscdm.h>
 34: #include <petscdmda.h>

 36: int main(int argc, char **argv)
 37: {
 38:   PetscMPIInt     rank;
 39:   PetscInt        M = 10, N = 8;
 40:   PetscBool       flg = PETSC_FALSE;
 41:   DM              da;
 42:   PetscViewer     viewer;
 43:   Vec             local, global;
 44:   PetscScalar     value;
 45:   DMBoundaryType  bx = DM_BOUNDARY_NONE, by = DM_BOUNDARY_NONE;
 46:   DMDAStencilType stype = DMDA_STENCIL_BOX;
 47: #if defined(PETSC_HAVE_MATLAB)
 48:   PetscViewer mviewer;
 49:   PetscMPIInt size;
 50: #endif

 53:   PetscInitialize(&argc, &argv, (char *)0, help);
 54:   PetscViewerDrawOpen(PETSC_COMM_WORLD, 0, "", 300, 0, 300, 300, &viewer);
 55: #if defined(PETSC_HAVE_MATLAB)
 56:   MPI_Comm_size(PETSC_COMM_WORLD, &size);
 57:   if (size == 1) PetscViewerMatlabOpen(PETSC_COMM_WORLD, "tmp.mat", FILE_MODE_WRITE, &mviewer);
 58: #endif

 60:   PetscOptionsGetBool(NULL, NULL, "-star_stencil", &flg, NULL);
 61:   if (flg) stype = DMDA_STENCIL_STAR;

 63:   /* Create distributed array and get vectors */
 64:   DMDACreate2d(PETSC_COMM_WORLD, bx, by, stype, M, N, PETSC_DECIDE, PETSC_DECIDE, 1, 1, NULL, NULL, &da);
 65:   DMSetFromOptions(da);
 66:   DMSetUp(da);
 67:   DMCreateGlobalVector(da, &global);
 68:   DMCreateLocalVector(da, &local);

 70:   value = -3.0;
 71:   VecSet(global, value);
 72:   DMGlobalToLocalBegin(da, global, INSERT_VALUES, local);
 73:   DMGlobalToLocalEnd(da, global, INSERT_VALUES, local);

 75:   MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
 76:   value = rank + 1;
 77:   VecScale(local, value);
 78:   DMLocalToGlobalBegin(da, local, ADD_VALUES, global);
 79:   DMLocalToGlobalEnd(da, local, ADD_VALUES, global);

 81:   flg = PETSC_FALSE;
 82:   PetscOptionsGetBool(NULL, NULL, "-view_global", &flg, NULL);
 83:   if (flg) { /* view global vector in natural ordering */
 84:     VecView(global, PETSC_VIEWER_STDOUT_WORLD);
 85:   }
 86:   DMView(da, viewer);
 87:   VecView(global, viewer);
 88: #if defined(PETSC_HAVE_MATLAB)
 89:   if (size == 1) {
 90:     DMView(da, mviewer);
 91:     VecView(global, mviewer);
 92:   }
 93: #endif

 95:   /* Free memory */
 96: #if defined(PETSC_HAVE_MATLAB)
 97:   if (size == 1) PetscViewerDestroy(&mviewer);
 98: #endif
 99:   PetscViewerDestroy(&viewer);
100:   VecDestroy(&local);
101:   VecDestroy(&global);
102:   DMDestroy(&da);
103:   PetscFinalize();
104:   return 0;
105: }

107: /*TEST

109:    test:
110:       requires: x
111:       nsize: 2
112:       args: -nox

114: TEST*/