/* 
Jonathan Hauenstein - University of Notre Dame
Center for Applied Mathematics Minicourse on Parallel Computing
April 24, May 1, May 8, 2008
Sample programs are designed for educational use 
*/

#include <stdio.h>
#include <stdlib.h>

int samples_in_circle(int num_samples)
{ // generates 'num_samples' sample points in [-1,1] x [-1,1]
  // and returns the number of them that are in the unit circle

  int i, count = 0;
  double x, y;

  // seed the random number generator
  srand(time(NULL));

  for (i = 0; i < num_samples; i++)
  { // generate x & y in [-1,1]
    x = 2 * (rand() / (RAND_MAX + 1.0) - 0.5);
    y = 2 * (rand() / (RAND_MAX + 1.0) - 0.5);

    // determine if (x,y) is in unit circle
    if (x*x + y*y <= 1)
      count++;
  }

  return count;
}