#include "mpi.h"
#include <stdio.h> 
#include <math.h>
#define INTERVALS 1000000000
int main( int argc, char *argv[] ) 
{ 
    int n=INTERVALS, myid, numprocs, i;
    double PI25DT = 3.141592653589793238462643; 
    double mypi, pi, h, sum, x;
    MPI_Init(&argc,&argv); 
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs); 
    MPI_Comm_rank(MPI_COMM_WORLD,&myid);
    MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
            h   = 1.0 / (double) n; 
            sum = 0.0; 
#pragma acc data copy(sum)
#pragma acc kernels loop reduction(+:sum)
            for (i = myid + 1; i <= n; i += numprocs) { 
                x = h * ((double)i - 0.5); 
                sum += (4.0 / (1.0 + x*x)); 
            } 
            mypi = h * sum; 
            MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, 
		       MPI_COMM_WORLD); 
            if (myid == 0)
                printf("pi is approximately %.16f, Error is %.16f\n",
                       pi, fabs(pi - PI25DT));
    MPI_Finalize(); 
    return 0; 
}