#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "mpi.h"

main(int argc, char* argv[])
{
  int           i;
  double t,t_start, t_end;

  int        my_rank;
  int        p;
  MPI_Status    status;
  double x,y,random_max;

  MPI_Init(&argc, &argv);
  MPI_Comm_rank(MPI_COMM_WORLD,&my_rank);
  MPI_Comm_size(MPI_COMM_WORLD,&p);

  if (argc < 2) {
    fprintf(stderr,"Usage: %s message\n",argv[0]);
    exit(1);
  }

  t_start = MPI_Wtime();

  srandom(69978+my_rank); /* we want different random numbers 
                             in each processor */
  random_max = 2147483648.0;
  x = ((double) random() / random_max);

  printf("The message from process %d is <%s>\n",my_rank,argv[1]);
  printf("and x in process %d is %lf\n",my_rank,x);

  if (my_rank > 0) {
    MPI_Send(&x,1,MPI_DOUBLE,
	     0, /* destination */
	     0, /* tag */
	     MPI_COMM_WORLD);
  } else {
    for (i=1;i<p; i++) {
      MPI_Recv(&y,1,MPI_DOUBLE, 
	       i,
	       0, /* tag */
	       MPI_COMM_WORLD,
	       &status);
      printf("Process 0 received value %lf from process %d\n",y,i);

    }


    /* now let's wait for a minute so the user can see 
       the program running */

    while (MPI_Wtime() - t_start < 60) ;

    t_end = MPI_Wtime();
    printf("Time in secs : %lf\n",t_end - t_start);


  }
  MPI_Finalize();
}