80 lines
2.7 KiB
Java
80 lines
2.7 KiB
Java
/*
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* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.util.Comparator;
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import java.util.random.RandomGenerator;
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import java.util.random.RandomGenerator.*;
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import java.util.random.RandomGeneratorFactory;
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/**
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* @test
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* @summary test bit sequences produced by clases that implement interface RandomGenerator
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* @bug 8248862
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* @run main RandomCanaryPi
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* @key randomness
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*/
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public class RandomCanaryPi {
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static double pi(RandomGenerator rng) {
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int N = 10000000;
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int k = 0;
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for (int i = 0; i < N; i++) {
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double x = rng.nextDouble();
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double y = rng.nextDouble();
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if (x * x + y * y <= 1.0) {
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k++;
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}
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}
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return 4.0 * (double)k / (double)N;
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}
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static int failed = 0;
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public static void main(String[] args) {
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RandomGeneratorFactory.all()
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.sorted(Comparator.comparing(RandomGeneratorFactory::name))
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.forEach(factory -> {
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RandomGenerator rng = factory.create();
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double pi = pi(rng);
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double delta = Math.abs(Math.PI - pi);
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boolean pass = delta < 1E-2;
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if (!pass) {
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System.err.println("Algorithm = " + factory.name() + " failed");
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System.err.println("Actual = " + Math.PI);
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System.err.println("Monte Carlo = " + pi);
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System.err.println("Delta = " + delta);
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System.err.println();
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failed++;
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}
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});
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if (failed != 0) {
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throw new RuntimeException(failed + " tests failed");
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}
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}
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}
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