mirror of https://github.com/jlizier/jidt
144 lines
5.1 KiB
Java
144 lines
5.1 KiB
Java
/*
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* Java Information Dynamics Toolkit (JIDT)
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* Copyright (C) 2017, Joseph T. Lizier
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* This class was originally distributed as part of the Apache Commons
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* Math3 library (3.6.1), under the Apache License Version 2.0, which is
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* copied below. This Apache 2 software is now included as a derivative
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* work in the GPLv3 licensed JIDT project, as per:
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* http://www.apache.org/licenses/GPL-compatibility.html
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*
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* The original Apache source code has been modified as follows:
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* -- We have modified package names to sit inside the JIDT structure.
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*/
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package infodynamics.utils.commonsmath3.random;
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/** This class implements the WELL19937c pseudo-random number generator
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* from François Panneton, Pierre L'Ecuyer and Makoto Matsumoto.
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* <p>This generator is described in a paper by François Panneton,
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* Pierre L'Ecuyer and Makoto Matsumoto <a
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* href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng.pdf">Improved
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* Long-Period Generators Based on Linear Recurrences Modulo 2</a> ACM
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* Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper
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* are in <a href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng-errata.txt">wellrng-errata.txt</a>.</p>
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* @see <a href="http://www.iro.umontreal.ca/~panneton/WELLRNG.html">WELL Random number generator</a>
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* @since 2.2
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*/
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public class Well19937c extends AbstractWell {
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/** Serializable version identifier. */
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private static final long serialVersionUID = -7203498180754925124L;
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/** Number of bits in the pool. */
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private static final int K = 19937;
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/** First parameter of the algorithm. */
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private static final int M1 = 70;
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/** Second parameter of the algorithm. */
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private static final int M2 = 179;
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/** Third parameter of the algorithm. */
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private static final int M3 = 449;
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/** Creates a new random number generator.
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* <p>The instance is initialized using the current time as the
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* seed.</p>
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*/
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public Well19937c() {
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super(K, M1, M2, M3);
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}
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/** Creates a new random number generator using a single int seed.
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* @param seed the initial seed (32 bits integer)
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*/
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public Well19937c(int seed) {
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super(K, M1, M2, M3, seed);
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}
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/** Creates a new random number generator using an int array seed.
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* @param seed the initial seed (32 bits integers array), if null
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* the seed of the generator will be related to the current time
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*/
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public Well19937c(int[] seed) {
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super(K, M1, M2, M3, seed);
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}
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/** Creates a new random number generator using a single long seed.
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* @param seed the initial seed (64 bits integer)
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*/
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public Well19937c(long seed) {
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super(K, M1, M2, M3, seed);
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}
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/** {@inheritDoc} */
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@Override
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protected int next(final int bits) {
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final int indexRm1 = iRm1[index];
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final int indexRm2 = iRm2[index];
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final int v0 = v[index];
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final int vM1 = v[i1[index]];
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final int vM2 = v[i2[index]];
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final int vM3 = v[i3[index]];
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final int z0 = (0x80000000 & v[indexRm1]) ^ (0x7FFFFFFF & v[indexRm2]);
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final int z1 = (v0 ^ (v0 << 25)) ^ (vM1 ^ (vM1 >>> 27));
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final int z2 = (vM2 >>> 9) ^ (vM3 ^ (vM3 >>> 1));
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final int z3 = z1 ^ z2;
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int z4 = z0 ^ (z1 ^ (z1 << 9)) ^ (z2 ^ (z2 << 21)) ^ (z3 ^ (z3 >>> 21));
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v[index] = z3;
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v[indexRm1] = z4;
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v[indexRm2] &= 0x80000000;
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index = indexRm1;
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// add Matsumoto-Kurita tempering
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// to get a maximally-equidistributed generator
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z4 ^= (z4 << 7) & 0xe46e1700;
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z4 ^= (z4 << 15) & 0x9b868000;
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return z4 >>> (32 - bits);
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}
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}
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