# include <cstdlib>
# include <iostream>
# include <iomanip>

using namespace std;

# include "mpi.h"

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

//****************************************************************************80

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

//****************************************************************************80
//
//  Purpose:
//
//    MAIN is the main program for BONES.
//
//  Discussion:
//
//    BONES is a simple demonstration of the use of MPI by a C++ program.
//
//    This program should be run on at least two processes.
//    Any processes beyond the first two will not be given any work.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    22 January 2003
//
//  Author:
//
//    John Burkardt
//
//  Reference:
//
//    William Gropp, Ewing Lusk, Anthony Skjellum,
//    Using MPI: Portable Parallel Programming with the
//    Message-Passing Interface,
//    Second Edition,
//    MIT Press, 1999,
//    ISBN: 0262571323.
//
{
  int count;
  float data[100];
  int dest;
  int i;
  int num_procs;
  int rank;
  MPI::Status status;
  int tag;
  float value[200];
//
//  Initialize MPI.
//
  MPI::Init ( argc, argv );
//
//  Determine this process's rank.
//
  rank = MPI::COMM_WORLD.Get_rank ( );
//
//  Have Process 0 say hello.
//
  if ( rank == 0 )
  {
    num_procs = MPI::COMM_WORLD.Get_size ( );

    cout << "\n";
    cout << "BONES:\n";
    cout << "  C++ version\n";
    cout << "  An MPI example program.\n";
    cout << "  The number of processes available is " << num_procs << "\n";
  }
//
//  Process 0 expects up to 200 real values, from any source.
//
  if ( rank == 0 ) 
  {
    tag = 55;
    MPI::COMM_WORLD.Recv ( value, 200, MPI::FLOAT, MPI::ANY_SOURCE, tag, 
      status );

    cout << "P:" << rank << " Got data from process " <<
      status.Get_source() << "\n";

    count = status.Get_count ( MPI::FLOAT );

    cout << "P:" << rank << " Got " << count << " elements.\n";

    cout << "P:" << rank << " value[5] = " << value[5] << "\n";
  }
//
//  Process 1 sends 100 real values to process 0.
//
  else if ( rank == 1 )
  {
    cout << "\n";
    cout << "P:" << rank << " - setting up data to send to process 0.\n";

    for ( i = 0; i < 100; i++ ) 
    {
      data[i] = i;
    }

    dest = 0;
    tag = 55;
    MPI::COMM_WORLD.Send ( data, 100, MPI::FLOAT, dest, tag );
  }
//
//  Any other process is idle.
//
  else
  {
    cout << "\n";
    cout << "P:" << rank << " - MPI has no work for me!\n";
  }

  MPI::Finalize ( );

  if ( rank == 0 )
  {
    cout << "\n";
    cout << "BONES:\n";
    cout << "  Normal end of execution.\n";
  }

  return 0;
}