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

  3: /*
  4:   MATLAB must be installed to configure PETSc to have MATLAB engine.
  5: Unless you have specific important reasons for using the MATLAB engine, we do not
  6: recommend it. If you want to use MATLAB for visualization and maybe a little post processing
  7: then you can use the socket viewer and send the data to MATLAB via that.

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

 12:      5  6   7   8   9
 13:      0  1   2   3   4

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

 17:     0  0   0  1   1
 18:     0  0   0  1   1

 20: So the global PETSc ordering is

 22:     3  4  5   8  9
 23:     0  1  2   6  7

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

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

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

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

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

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

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

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

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

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

106: /*TEST

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

113: TEST*/