The listing of second.c

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include "mpi.h"
 
double f(a)
double a;
{
   return (4.0 / (1.0 + a*a));
}
 
int main ( int argc, char **argv )
{
    int pool_size, my_rank, host_rank, destination, source, node_name_length,
        *host_rank_ptr, found_flag, int_buffer[BUFSIZ];
    char char_buffer[BUFSIZ], my_node_name[BUFSIZ], console_name[BUFSIZ],
         host_name[BUFSIZ]; 
    MPI_Status status;
    boolean_t i_am_the_master = B_FALSE; 
 
#include "preamble.c"
 
    { 
       int n, i;
       double mypi, pi, h, sum, x, a;
 
       if (i_am_the_master) {
          printf("Enter the number of intervals: ");
          scanf("%d",&n);
          if (n==0) n=100;
       }
 
       MPI_Bcast(&n, 1, MPI_INT, host_rank, MPI_COMM_WORLD);
 
       h   = 1.0 / (double) n;
       sum = 0.0;
       for (i = my_rank + 1; i <= n; i += pool_size) {
          x = h * ((double)i - 0.5);
          sum += f(x);
       }
       mypi = h * sum;
 
       MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, host_rank,
                  MPI_COMM_WORLD);
 
       if (i_am_the_master) printf("pi is approximately %.16f\n", pi);
    }
 
    MPI_Finalize ();
}