//============================================================================
// Name        : serial_pi_calc.c
// Author      : Morteza Zakeri
// Version     : 1.0.0
// Copyright   : All right received.
// Description : SERIAL PI CACULATION in C, Ansi-style
//============================================================================

#include <iostream>
#include <stdio.h>
#include <stdlib.h> // include rand function

#define sqr(x)	((x)*(x))
using namespace std;

double cal_pi_serial(int darts)
{
	double x_coord,     /* x coordinate, between -1 and 1  */
		y_coord,		/* y coordinate, between -1 and 1  */
		pi,             /* pi  */
		r;              /* random number scaled between 0 and 1  */

	int score,          /* number of darts that hit circle */
		n;

	score = 0;

	for (n = 1; n <= darts; n++)
	{
		/* generate random numbers for x and y coordinates */
		r = (double)rand() / (double)RAND_MAX;
		x_coord = (2.0 * r) - 1.0;

		r = (double)rand() / (double)RAND_MAX;
		y_coord = (2.0 * r) - 1.0;

		/* if dart lands in circle, increment score */
		if ((sqr(x_coord) + sqr(y_coord)) <= 1.0)
			score++;
	}

	/* calculate pi */
	pi = 4.0 * (double)score / (double)darts;
	return(pi);
}


#define DARTS 100000
#define ROUNDS 1000

int main()
{
	double pi = 0;          	/* average of pi after "darts" is thrown */
	double pi_avg = 0;       	/* average pi value for all iterations */

	srandom (5);                /* seed the random number generator */

	for (int i = 0; i < ROUNDS; i++)
	{
	   /* Perform pi calculation on serial processor */
	   pi = cal_pi_serial(DARTS);

	   pi_avg = ((pi_avg * i) + pi) / (i + 1);

	   //printf(" After %3d throws, average value of pi = %10.8f\n", (DARTS * (i + 1)), avepi);
	}
	printf(" Final PI = %10.8f\n", pi_avg);

	printf("\nReal value of PI: 3.1415926535897 \n");

	return 0;
}