/*******************************************************************************
 * This is a simple serial version of computing pi using the Monte Carlo Method
 * The model asks the user to enter the number of iterations to use for 
 * estimating pi
 * 
 * Mobeen Ludin
 *
 ******************************************************************************/

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <omp.h>
#define SEED 35791246

int main (int argc, char **argv){
    double start_time, end_time, time_diff;
    int num_iteration = 0;
    double x, y;
    int i;
    int count = 0; // Number of points in the first quadrant of unit circle
    double z, pi;

    printf("Please enter the number of iterations used to compute pi: ");
    scanf("%d",&num_iteration);

    // Record the start time from here on:
    start_time = omp_get_wtime();

    srandom(SEED); // this will initialize some random numbers
    count = 0;

    for(i=0; i<num_iteration; i++){
        x = (double)random()/RAND_MAX;
        y = (double)random()/RAND_MAX; 
        z = (x*x) + (y*y);
        if (z <=1) count++;
    }
    pi=(double)count/num_iteration*4;

    //End recording the time here.
    end_time = omp_get_wtime();
    time_diff = end_time - start_time;

    printf("Number of iterations is = %d \n\n", num_iteration);
    printf("Estimated value of PI is %g - (%17.15f)\n\n",pi,pi);
    printf("Accurate value of PI from math.h is: %17.15f \n\n", M_PI);

    printf("Difference between computed pi and math.h M_PI = %17.15f\n\n",
            fabs(pi - M_PI));

    printf("Time to compute = %f seconds\n\n", time_diff);

    return EXIT_SUCCESS;
}