pi.dart

// Estimate PI using monte carlo simulation
// See http://www.davidrobles.net/blog/2014/06/22/estimating-pi-using-monte-carlo-simulations/

import 'dart:math';

Random rnd = new Random();

// Return a random point within [-1, 1] coordinate plane
class UnitPoint {
  double x;
  double y;

  UnitPoint() {
    this.x = rnd.nextDouble() * (rnd.nextInt(2) == 0 ? -1 : 1);
    this.y = rnd.nextDouble() * (rnd.nextInt(2) == 0 ? -1 : 1);
  }
  
  String toString() {
    return "x: ${x.toStringAsFixed(2)} y: ${y.toStringAsFixed(2)}";
  }
}


void main() {
  
  int N = 100000000;
	var inCircle = (UnitPoint p) => (p.x*p.x + p.y*p.y) < 1.0;
  
  print("Started: ${new DateTime.now()}");
  int C = 0;
  for (int i = 0; i < N; i++) {
    if (inCircle(new UnitPoint())) {
      C++;
    }
  }
  
  print("N = ${N}");
  print("C = ${C}");
  print("estimated pi value = ${(4 * C / N).toStringAsFixed(5)}");
  print("Ended: ${new DateTime.now()}");
}