Actual source code: ex10.c
petsc-3.4.2 2013-07-02

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

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

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

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

     34:   /* Initialize the Petsc context */
     35:   PetscInitialize(&argc,&argv,(char*)0,help);

     37:   /* Build of the DMDA */
     38:   DMDACreate2d(PETSC_COMM_WORLD, DMDA_BOUNDARY_NONE, DMDA_BOUNDARY_NONE,DMDA_STENCIL_STAR,Nx,Ny,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da2D);

     40:   /* Set the coordinates */
     41:   DMDASetUniformCoordinates(da2D, 0.0, 1.0, 0.0, 1.0, 0.0, 0.0);

     43:   /* Declare gauss as a DMDA component */
     44:   DMCreateGlobalVector(da2D,&gauss);
     45:   PetscObjectSetName((PetscObject) gauss, "pressure");

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

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

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

     62:   /* Create the HDF5 viewer */
     63:   PetscViewerHDF5Open(PETSC_COMM_WORLD,"gauss.h5",FILE_MODE_WRITE,&H5viewer);

     65:   /* Write the H5 file */
     66:   VecView(gauss,H5viewer);

     68:   /* Cleaning stage */
     69:   PetscViewerDestroy(&H5viewer);
     70:   VecDestroy(&gauss);
     71:   DMDestroy(&da2D);
     72:   PetscFinalize();
     73:   return 0;
     74: }