Ben Konyi
700254996f
Change-Id: Ibc64b3371353850ff15153c06970a30e47a24888 Reviewed-on: https://dart-review.googlesource.com/c/89900 Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Ben Konyi <bkonyi@google.com>
50 lines
1.3 KiB
Dart
50 lines
1.3 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// Test that the default PRNG does converge towards Pi when doing a Monte Carlo
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// simulation.
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import "package:expect/expect.dart";
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import 'dart:math';
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var known_bad_seeds = const [50051, 55597, 59208];
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void main([args]) {
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// Select a seed either from the argument passed in or
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// otherwise a random seed.
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var seed = -1;
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if ((args != null) && (args.length > 0)) {
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seed = int.parse(args[0]);
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} else {
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var seed_prng = new Random();
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while (seed == -1) {
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seed = seed_prng.nextInt(1 << 16);
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if (known_bad_seeds.contains(seed)) {
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// Reset seed and try again.
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seed = -1;
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}
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}
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}
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// Setup the PRNG for the Monte Carlo simulation.
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print("pi_test seed: $seed");
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var prng = new Random(seed);
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var outside = 0;
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var inside = 0;
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for (var i = 0; i < 600000; i++) {
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var x = prng.nextDouble();
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var y = prng.nextDouble();
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if ((x * x) + (y * y) < 1.0) {
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inside++;
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} else {
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outside++;
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}
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}
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// Mmmmh, Pie!
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var pie = 4.0 * (inside / (inside + outside));
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print("$pie");
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Expect.isTrue(((pi - 0.009) < pie) && (pie < (pi + 0.009)));
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}
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