Actual source code: ex10.c
petsc-3.12.4 2020-02-04
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      1: /*
      2:    Demonstrates using the HDF5 viewer with a DMDA Vec
      3:  - create a global vector containing a gauss profile (exp(-x^2-y^2))
      4:  - write the global vector in a hdf5 file

      6:    The resulting file gauss.h5 can be viewed with Visit (an open source visualization package)
      7:    Or with some versions of MATLAB with data=hdfread('gauss.h5','pressure'); mesh(data);

      9:    The file storage of the vector is independent of the number of processes used.
     10:  */

     12:  #include <petscdm.h>
     13:  #include <petscdmda.h>
     14:  #include <petscsys.h>
     15: #include <petscviewerhdf5.h>

     17: static char help[] = "Test to write HDF5 file from PETSc DMDA Vec.\n\n";

     19: int main(int argc,char **argv)
     20: {
     22:   DM             da2D;
     23:   PetscInt       i,j,ixs, ixm, iys, iym;
     24:   PetscViewer    H5viewer;
     25:   PetscScalar    xm    = -1.0, xp=1.0;
     26:   PetscScalar    ym    = -1.0, yp=1.0;
     27:   PetscScalar    value = 1.0,dx,dy;
     28:   PetscInt       Nx    = 40, Ny=40;
     29:   Vec            gauss,input;
     30:   PetscScalar    **gauss_ptr;
     31:   PetscReal      norm;
     32:   const char     *vecname;

     34:   dx=(xp-xm)/(Nx-1);
     35:   dy=(yp-ym)/(Ny-1);

     37:   /* Initialize the Petsc context */
     38:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
     39:   DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,Nx,Ny,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da2D);
     40:   DMSetFromOptions(da2D);
     41:   DMSetUp(da2D);

     43:   /* Set the coordinates */
     44:   DMDASetUniformCoordinates(da2D, 0.0, 1.0, 0.0, 1.0, 0.0, 0.0);

     46:   /* Declare gauss as a DMDA component */
     47:   DMCreateGlobalVector(da2D,&gauss);
     48:   PetscObjectSetName((PetscObject) gauss, "pressure");

     50:   /* Initialize vector gauss with a constant value (=1) */
     51:   VecSet(gauss,value);

     53:   /* Get the coordinates of the corners for each process */
     54:   DMDAGetCorners(da2D, &ixs, &iys, 0, &ixm, &iym, 0);

     56:   /* Build the gaussian profile (exp(-x^2-y^2)) */
     57:   DMDAVecGetArray(da2D,gauss,&gauss_ptr);
     58:   for (j=iys; j<iys+iym; j++) {
     59:     for (i=ixs; i<ixs+ixm; i++) {
     60:       gauss_ptr[j][i]=PetscExpScalar(-(xm+i*dx)*(xm+i*dx)-(ym+j*dy)*(ym+j*dy));
     61:     }
     62:   }
     63:   DMDAVecRestoreArray(da2D,gauss,&gauss_ptr);

     65:   /* Create the HDF5 viewer */
     66:   PetscViewerHDF5Open(PETSC_COMM_WORLD,"gauss.h5",FILE_MODE_WRITE,&H5viewer);
     67:   PetscViewerSetFromOptions(H5viewer);

     69:   /* Write the H5 file */
     70:   VecView(gauss,H5viewer);

     72:   /* Close the viewer */
     73:   PetscViewerDestroy(&H5viewer);

     75:   VecDuplicate(gauss,&input);
     76:   PetscObjectGetName((PetscObject)gauss,&vecname);
     77:   PetscObjectSetName((PetscObject)input,vecname);

     79:   /* Create the HDF5 viewer for reading */
     80:   PetscViewerHDF5Open(PETSC_COMM_WORLD,"gauss.h5",FILE_MODE_READ,&H5viewer);
     81:   PetscViewerSetFromOptions(H5viewer);
     82:   VecLoad(input,H5viewer);
     83:   PetscViewerDestroy(&H5viewer);

     85:   VecAXPY(input,-1.0,gauss);
     86:   VecNorm(input,NORM_2,&norm);
     87:   if (norm > 1.e-6) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_PLIB,"Vec read in does not match vector written out");

     89:   VecDestroy(&input);
     90:   VecDestroy(&gauss);
     91:   DMDestroy(&da2D);
     92:   PetscFinalize();
     93:   return ierr;
     94: }

     97: /*TEST

     99:       build:
    100:          requires: hdf5 !define(PETSC_USE_CXXCOMPLEX)

    102:       test:
    103:          nsize: 4

    105:       test:
    106:          nsize: 4
    107:          suffix: 2
    108:          args: -viewer_hdf5_base_dimension2
    109:          output_file: output/ex10_1.out

    111:       test:
    112:          nsize: 4
    113:          suffix: 3
    114:          args: -viewer_hdf5_sp_output
    115:          output_file: output/ex10_1.out

    117: TEST*/