// @HEADER
// ***********************************************************************
// 
//                      Didasko Tutorial Package
//                 Copyright (2005) Sandia Corporation
// 
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
// 
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//  
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
// Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
// 
// ***********************************************************************
// @HEADER

// Epetra_Export classes
// This code should be run with at least two processes

#include "Didasko_ConfigDefs.h"
#if defined(HAVE_DIDASKO_EPETRA)

#include "Epetra_ConfigDefs.h"
#ifdef HAVE_MPI
#include "mpi.h"
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_Map.h"
#include "Epetra_Vector.h"
#include "Epetra_Export.h"

int main(int argc, char *argv[]) {

#ifdef HAVE_MPI
  MPI_Init(&argc, &argv);
  Epetra_MpiComm Comm(MPI_COMM_WORLD);
#else
  Epetra_SerialComm Comm;
#endif

  int NumGlobalElements = 4; // global dimension of the problem

  int NumMyElements; // local nodes
  Epetra_IntSerialDenseVector MyGlobalElements;

  if( Comm.MyPID() == 0 ) {
    NumMyElements = 3;
    MyGlobalElements.Size(NumMyElements);
    MyGlobalElements[0] = 0;
    MyGlobalElements[1] = 1;
    MyGlobalElements[2] = 2;
  } else {
    NumMyElements = 3;
    MyGlobalElements.Size(NumMyElements);
    MyGlobalElements[0] = 1;
    MyGlobalElements[1] = 2;
    MyGlobalElements[2] = 3;
  }

  // create a map
  Epetra_Map Map(-1,MyGlobalElements.Length(),
         MyGlobalElements.Values(),0, Comm);

  // create a vector based on map
  Epetra_Vector xxx(Map);
  for( int i=0 ; i<NumMyElements ; ++i )
    xxx[i] = 10*( Comm.MyPID()+1 );

  if( Comm.MyPID() == 0 ){
    double val = 12;
    int pos = 3;
    xxx.SumIntoGlobalValues(1,0,&val,&pos);
  }
  
  cout << xxx;

  // create a target map, in which all the elements are on proc 0
  int NumMyElements_target;

  if( Comm.MyPID() == 0 )
    NumMyElements_target = NumGlobalElements;
  else
    NumMyElements_target = 0;

  Epetra_Map TargetMap(-1,NumMyElements_target,0,Comm);

  Epetra_Export Exporter(Map,TargetMap);

  // work on vectors
  Epetra_Vector yyy(TargetMap);

  yyy.Export(xxx,Exporter,Add);

  cout << yyy;

#ifdef HAVE_MPI
  MPI_Finalize();
#endif

  return(EXIT_SUCCESS);

}

#else

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
  puts("Please configure Didasko with:\n"
       "--enable-epetra");

  return 0;
}

#endif

---