Date: 2026-05-01T06:11:50+00:00

Actual source code: ex9.c

      1: static char help[] = "Demonstrates HDF5 vector input/output\n\n";

      3: #include <petscsys.h>
      4: #include <petscdm.h>
      5: #include <petscdmda.h>
      6: #include <petscviewerhdf5.h>

      8: int main(int argc, char **argv)
      9: {
     10:   PetscViewer viewer;
     11:   DM          da;
     12:   Vec         global, local, global2;
     13:   PetscMPIInt rank;
     14:   PetscBool   flg;
     15:   PetscInt    ndof;

     17:   /*
     18:     Every PETSc routine should begin with the PetscInitialize() routine.
     19:     argc, argv - These command line arguments are taken to extract the options
     20:                  supplied to PETSc and options supplied to MPI.
     21:     help       - When PETSc executable is invoked with the option -help,
     22:                  it prints the various options that can be applied at
     23:                  runtime.  The user can use the "help" variable place
     24:                  additional help messages in this printout.
     25:   */
     26:   PetscFunctionBeginUser;
     27:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
     28:   /* Get number of DOF's from command line */
     29:   PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "DMDA VecView/VecLoad example", "");
     30:   {
     31:     ndof = 1;
     32:     PetscCall(PetscOptionsBoundedInt("-ndof", "Number of DOF's in DMDA", "", ndof, &ndof, NULL, 1));
     33:   }
     34:   PetscOptionsEnd();

     36:   /* Create a DMDA and an associated vector */
     37:   PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, 100, 90, PETSC_DECIDE, PETSC_DECIDE, ndof, 1, NULL, NULL, &da));
     38:   PetscCall(DMSetFromOptions(da));
     39:   PetscCall(DMSetUp(da));
     40:   PetscCall(DMCreateGlobalVector(da, &global));
     41:   PetscCall(DMCreateLocalVector(da, &local));
     42:   PetscCall(VecSet(global, -1.0));
     43:   PetscCall(DMGlobalToLocalBegin(da, global, INSERT_VALUES, local));
     44:   PetscCall(DMGlobalToLocalEnd(da, global, INSERT_VALUES, local));
     45:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
     46:   PetscCall(VecScale(local, rank + 1));
     47:   PetscCall(DMLocalToGlobalBegin(da, local, ADD_VALUES, global));
     48:   PetscCall(DMLocalToGlobalEnd(da, local, ADD_VALUES, global));

     50:   /* Create the HDF5 viewer for writing */
     51:   PetscCall(PetscViewerHDF5Open(PETSC_COMM_WORLD, "hdf5output.h5", FILE_MODE_WRITE, &viewer));
     52:   PetscCall(PetscViewerSetFromOptions(viewer));

     54:   /* Write the Vec without one extra dimension for BS */
     55:   PetscCall(PetscViewerHDF5SetBaseDimension2(viewer, PETSC_FALSE));
     56:   PetscCall(PetscObjectSetName((PetscObject)global, "noBsDim"));
     57:   PetscCall(VecView(global, viewer));

     59:   /* Write the Vec with one extra, 1-sized, dimension for BS */
     60:   PetscCall(PetscViewerHDF5SetBaseDimension2(viewer, PETSC_TRUE));
     61:   PetscCall(PetscObjectSetName((PetscObject)global, "bsDim"));
     62:   PetscCall(VecView(global, viewer));

     64:   PetscCall(PetscViewerDestroy(&viewer));
     65:   PetscCallMPI(MPI_Barrier(PETSC_COMM_WORLD));
     66:   PetscCall(VecDuplicate(global, &global2));

     68:   /* Create the HDF5 viewer for reading */
     69:   PetscCall(PetscViewerHDF5Open(PETSC_COMM_WORLD, "hdf5output.h5", FILE_MODE_READ, &viewer));
     70:   PetscCall(PetscViewerSetFromOptions(viewer));

     72:   /* Load the Vec without the BS dim and compare */
     73:   PetscCall(PetscObjectSetName((PetscObject)global2, "noBsDim"));
     74:   PetscCall(VecLoad(global2, viewer));

     76:   PetscCall(VecEqual(global, global2, &flg));
     77:   if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Error: Vectors are not equal\n"));

     79:   /* Load the Vec with one extra, 1-sized, BS dim and compare */
     80:   PetscCall(PetscObjectSetName((PetscObject)global2, "bsDim"));
     81:   PetscCall(VecLoad(global2, viewer));
     82:   PetscCall(PetscViewerDestroy(&viewer));

     84:   PetscCall(VecEqual(global, global2, &flg));
     85:   if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Error: Vectors are not equal\n"));

     87:   /* clean up and exit */
     88:   PetscCall(VecDestroy(&local));
     89:   PetscCall(VecDestroy(&global));
     90:   PetscCall(VecDestroy(&global2));
     91:   PetscCall(DMDestroy(&da));

     93:   PetscCall(PetscFinalize());
     94:   return 0;
     95: }

     97: /*TEST

     99:       build:
    100:          requires: hdf5

    102:       test:
    103:          nsize: 4
    104:          output_file: output/empty.out

    106:       test:
    107:          nsize: 4
    108:          suffix: 2
    109:          args: -ndof 2
    110:          output_file: output/empty.out

    112: TEST*/