// Compute pi by dropping balls onto a unit square and counting
// the number that land in the inscribe square.
public class Pi {
  public static void main (String[] args) {
    final long NUM_BALLS = (long)1.0E11; // could read this in
    long inside = 0;                     // number in circle
    double x, y;
    System.out.println("     Dropped      Inside  Estimate of pi");
    for (long dropped=1; dropped<=NUM_BALLS; dropped++) {
      x = Math.random();
      y = Math.random();
      if (dist(x,y,0.5,0.5)<0.5)
        inside++;
      if (interesting(dropped))
        System.out.printf("%12d%12d%14.10f\n",
                          dropped,inside,estimate(dropped,inside));
    }
  }
  public static double dist(double x1, double y1, double x2, double y2) {
    return Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
  }
  public static double estimate(long dropped, long inside) {
    return 4.0*((double)inside / (double)dropped);
  }
  public static boolean interesting(long x) {
    double l10 = Math.log10(x);    // Powers of 10 = l10 an integer
    return Math.abs(l10 - Math.rint(l10)) < 1.0E-14;
  }
}
// Local Variables:
// c-basic-offset: 2
// indent-tabs-mode: nil
// compile-command: "javac Pi.java  && time java Pi"
// End: