static char help[] = "Tests binary I/O of vectors and illustrates the use of user-defined event logging.\n\n";

#include <petscvec.h>

/* Note:  Most applications would not read and write a vector within
  the same program.  This example is intended only to demonstrate
  both input and output. */

#undef __FUNCT__
#define __FUNCT__ "main"
int main(int argc,char **args)
{
  PetscErrorCode ierr;
  PetscMPIInt    rank,size;
  PetscInt       i,m = 10,low,high,ldim,iglobal;
  PetscScalar    v;
  Vec            u;
  PetscViewer    viewer;
#if defined(PETSC_USE_LOG)
  PetscLogEvent  VECTOR_GENERATE,VECTOR_READ;
#endif

  PetscInitialize(&argc,&args,(char *)0,help);
  ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
  ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);CHKERRQ(ierr);

  /* PART 1:  Generate vector, then write it in binary format */

  ierr = PetscLogEventRegister("Generate Vector",VEC_CLASSID,&VECTOR_GENERATE);CHKERRQ(ierr);
  ierr = PetscLogEventBegin(VECTOR_GENERATE,0,0,0,0);CHKERRQ(ierr);
  /* Generate vector */
  ierr = VecCreate(PETSC_COMM_WORLD,&u);CHKERRQ(ierr);
  ierr = VecSetSizes(u,PETSC_DECIDE,m);CHKERRQ(ierr);
  ierr = VecSetFromOptions(u);CHKERRQ(ierr);
  ierr = VecGetOwnershipRange(u,&low,&high);CHKERRQ(ierr);
  ierr = VecGetLocalSize(u,&ldim);CHKERRQ(ierr);
  for (i=0; i<ldim; i++) {
    iglobal = i + low;
    v = (PetscScalar)(i + 100*rank);
    ierr = VecSetValues(u,1,&iglobal,&v,INSERT_VALUES);CHKERRQ(ierr);
  }
  ierr = VecAssemblyBegin(u);CHKERRQ(ierr);
  ierr = VecAssemblyEnd(u);CHKERRQ(ierr);
  ierr = VecView(u,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);

  ierr = PetscPrintf(PETSC_COMM_WORLD,"writing vector in binary to vector.dat ...\n");CHKERRQ(ierr);
  ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_WRITE,&viewer);CHKERRQ(ierr);
  ierr = VecView(u,viewer);CHKERRQ(ierr);
  ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
  ierr = VecDestroy(&u);CHKERRQ(ierr);
  /*  ierr = PetscOptionsClear();CHKERRQ(ierr);*/
  ierr = PetscOptionsSetValue("-viewer_binary_mpiio","");CHKERRQ(ierr); 

  ierr = PetscLogEventEnd(VECTOR_GENERATE,0,0,0,0);CHKERRQ(ierr);

  /* PART 2:  Read in vector in binary format */

  /* Read new vector in binary format */
  ierr = PetscLogEventRegister("Read Vector",VEC_CLASSID,&VECTOR_READ);CHKERRQ(ierr);
  ierr = PetscLogEventBegin(VECTOR_READ,0,0,0,0);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"reading vector in binary from vector.dat ...\n");CHKERRQ(ierr);
  ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_READ,&viewer);CHKERRQ(ierr);
  ierr = VecCreate(PETSC_COMM_WORLD,&u);CHKERRQ(ierr);
  ierr = VecLoad(u,viewer);CHKERRQ(ierr);
  ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
  ierr = PetscLogEventEnd(VECTOR_READ,0,0,0,0);CHKERRQ(ierr);
  ierr = VecView(u,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);

  /* Free data structures */
  ierr = VecDestroy(&u);CHKERRQ(ierr);
  ierr = PetscFinalize();
  return 0;
}