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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 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 | 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. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 // Test that the default PRNG does uniformly distribute values when not using | 5 // Test that the default PRNG does uniformly distribute values when not using |
6 // a power of 2. | 6 // a power of 2. |
7 | 7 |
8 // Library tag to allow Dartium to run the test. | 8 // Library tag to allow Dartium to run the test. |
9 #library("low_test.dart"); | 9 library low_test; |
10 | 10 |
11 #import("dart:math"); | 11 import 'dart:math'; |
12 | 12 |
13 void main() { | 13 void main() { |
14 var n = (2 * (1<<32)) ~/ 3; | 14 var n = (2 * (1<<32)) ~/ 3; |
15 var n2 = n ~/ 2; | 15 var n2 = n ~/ 2; |
16 | 16 |
17 var iterations = 200000; | 17 var iterations = 200000; |
18 | 18 |
19 var seed = new Random().nextInt((1<<32) - 1); | 19 var seed = new Random().nextInt((1<<32) - 1); |
20 print("low_test seed: $seed"); | 20 print("low_test seed: $seed"); |
21 var prng = new Random(seed); | 21 var prng = new Random(seed); |
22 | 22 |
23 var low = 0; | 23 var low = 0; |
24 for (var i = 0; i < iterations; i++) { | 24 for (var i = 0; i < iterations; i++) { |
25 if (prng.nextInt(n) < n2) { | 25 if (prng.nextInt(n) < n2) { |
26 low++; | 26 low++; |
27 } | 27 } |
28 } | 28 } |
29 | 29 |
30 var diff = (low - (iterations ~/ 2)).abs(); | 30 var diff = (low - (iterations ~/ 2)).abs(); |
31 print("$low, $diff"); | 31 print("$low, $diff"); |
32 Expect.isTrue(diff < (iterations ~/ 20)); | 32 Expect.isTrue(diff < (iterations ~/ 20)); |
33 } | 33 } |
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