OLD | NEW |
| (Empty) |
1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 // Test that the default PRNG does converge towards Pi when doing a Monte Carlo | |
6 // simulation. | |
7 | |
8 // Library tag to allow Dartium to run the test. | |
9 library pi_test; | |
10 | |
11 import "package:expect/expect.dart"; | |
12 import 'dart:math'; | |
13 | |
14 var known_bad_seeds = const [50051, 55597, 59208]; | |
15 | |
16 void main([args]) { | |
17 // Select a seed either from the argument passed in or | |
18 // otherwise a random seed. | |
19 var seed = -1; | |
20 if ((args != null) && (args.length > 0)) { | |
21 seed = int.parse(args[0]); | |
22 } else { | |
23 var seed_prng = new Random(); | |
24 while (seed == -1) { | |
25 seed = seed_prng.nextInt(1 << 16); | |
26 if (known_bad_seeds.contains(seed)) { | |
27 // Reset seed and try again. | |
28 seed = -1; | |
29 } | |
30 } | |
31 } | |
32 | |
33 // Setup the PRNG for the Monte Carlo simulation. | |
34 print("pi_test seed: $seed"); | |
35 var prng = new Random(seed); | |
36 | |
37 var outside = 0; | |
38 var inside = 0; | |
39 for (var i = 0; i < 600000; i++) { | |
40 var x = prng.nextDouble(); | |
41 var y = prng.nextDouble(); | |
42 if ((x * x) + (y * y) < 1.0) { | |
43 inside++; | |
44 } else { | |
45 outside++; | |
46 } | |
47 } | |
48 // Mmmmh, Pie! | |
49 var pie = 4.0 * (inside / (inside + outside)); | |
50 print("$pie"); | |
51 Expect.isTrue(((PI - 0.009) < pie) && (pie < (PI + 0.009))); | |
52 } | |
OLD | NEW |