/**********************************************************
 File:          hello_world.cc                        
 Description:   Every process writes hello and its rank.
                                                        
 Author:        Dana Vrajitoru                          
 Class:         B424 B524
 Last update:   September 14, 2004
**********************************************************/

#include <mpi.h>
#include <cmath>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;

/**********************************************************/
/* The function that writes the message on the screen.    */
void Write_message(int rank, char *message)
{
  cout << message << " from process number " << rank << endl;
}

/**********************************************************/
/* Main                                                   */

int main(int argc, char **argv)
{
  double time;
  int mpirank, mpisize;
  int n=0;

  /* Initialize MPI */
  MPI_Init (&argc, &argv);
  
  /* Get the rank of this process */
  MPI_Comm_rank (MPI_COMM_WORLD, &mpirank);
  
  /* Get nb of processes */
  MPI_Comm_size (MPI_COMM_WORLD, &mpisize);

  /* Each process writes hello and then waits for all of the others */
  time = MPI_Wtime();
  Write_message(mpirank, "Hello");
  MPI_Barrier(MPI_COMM_WORLD);
  Write_message(mpirank, "after the barrier");
  if (mpirank == 0)
    n = 5;
  MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
  cout << "n is equal to " << n << " for process " << mpirank << endl;
  time = MPI_Wtime() - time;
  
  if (mpirank==0) 
    cout << "This program has run on " << mpisize
	 << " processes in " << time << " seconds." << endl;

  /* Finalize MPI */
  MPI_Finalize ();
  return 0;
}

/* End of the program                                     */
/**********************************************************/