/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3.random;


This class implements the WELL512a pseudo-random number generator from François Panneton, Pierre L'Ecuyer and Makoto Matsumoto.

This generator is described in a paper by François Panneton, Pierre L'Ecuyer and Makoto Matsumoto Improved Long-Period Generators Based on Linear Recurrences Modulo 2 ACM Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper are in wellrng-errata.txt.

See Also:
Since:2.2
/** This class implements the WELL512a pseudo-random number generator * from Fran&ccedil;ois Panneton, Pierre L'Ecuyer and Makoto Matsumoto. * <p>This generator is described in a paper by Fran&ccedil;ois Panneton, * Pierre L'Ecuyer and Makoto Matsumoto <a * href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng.pdf">Improved * Long-Period Generators Based on Linear Recurrences Modulo 2</a> ACM * Transactions on Mathematical Software, 32, 1 (2006). The errata for the paper * are in <a href="http://www.iro.umontreal.ca/~lecuyer/myftp/papers/wellrng-errata.txt">wellrng-errata.txt</a>.</p> * @see <a href="http://www.iro.umontreal.ca/~panneton/WELLRNG.html">WELL Random number generator</a> * @since 2.2 */
public class Well512a extends AbstractWell {
Serializable version identifier.
/** Serializable version identifier. */
private static final long serialVersionUID = -6104179812103820574L;
Number of bits in the pool.
/** Number of bits in the pool. */
private static final int K = 512;
First parameter of the algorithm.
/** First parameter of the algorithm. */
private static final int M1 = 13;
Second parameter of the algorithm.
/** Second parameter of the algorithm. */
private static final int M2 = 9;
Third parameter of the algorithm.
/** Third parameter of the algorithm. */
private static final int M3 = 5;
Creates a new random number generator.

The instance is initialized using the current time as the seed.

/** Creates a new random number generator. * <p>The instance is initialized using the current time as the * seed.</p> */
public Well512a() { super(K, M1, M2, M3); }
Creates a new random number generator using a single int seed.
Params:
  • seed – the initial seed (32 bits integer)
/** Creates a new random number generator using a single int seed. * @param seed the initial seed (32 bits integer) */
public Well512a(int seed) { super(K, M1, M2, M3, seed); }
Creates a new random number generator using an int array seed.
Params:
  • seed – the initial seed (32 bits integers array), if null the seed of the generator will be related to the current time
/** Creates a new random number generator using an int array seed. * @param seed the initial seed (32 bits integers array), if null * the seed of the generator will be related to the current time */
public Well512a(int[] seed) { super(K, M1, M2, M3, seed); }
Creates a new random number generator using a single long seed.
Params:
  • seed – the initial seed (64 bits integer)
/** Creates a new random number generator using a single long seed. * @param seed the initial seed (64 bits integer) */
public Well512a(long seed) { super(K, M1, M2, M3, seed); }
{@inheritDoc}
/** {@inheritDoc} */
@Override protected int next(final int bits) { final int indexRm1 = iRm1[index]; final int vi = v[index]; final int vi1 = v[i1[index]]; final int vi2 = v[i2[index]]; final int z0 = v[indexRm1]; // the values below include the errata of the original article final int z1 = (vi ^ (vi << 16)) ^ (vi1 ^ (vi1 << 15)); final int z2 = vi2 ^ (vi2 >>> 11); final int z3 = z1 ^ z2; final int z4 = (z0 ^ (z0 << 2)) ^ (z1 ^ (z1 << 18)) ^ (z2 << 28) ^ (z3 ^ ((z3 << 5) & 0xda442d24)); v[index] = z3; v[indexRm1] = z4; index = indexRm1; return z4 >>> (32 - bits); } }