// MonteCarloPI.cpp : Defines the entry point for the console application.
// This is an iterative method to calculate PI.  The more iterations, the more accurate

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

int _tmain(int argc, _TCHAR* argv[])

{
   int niter=0;
   double x, y;
   int i, count=0; //number of points 1st quadrant of unit circle 
   double z;
   double pi;

   printf("Enter, number of iterations: ");
   scanf_s("%d",&niter);

   /* initialize random numbers */
   srand(SEED);

   count=0;
   for ( i=0; i<niter; i++) {
      x = (double)rand() / RAND_MAX;
      y = (double)rand() / RAND_MAX;
      z = pow(x,2) + pow(y,2);
      if (z<=1) count++;
      }

   pi=(double)count / niter*4;
   printf("Number of Iterations= %d , PI(approximation)= %g \n",niter,pi);

   return 0;
}