001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.rng.core.source64;
019
020/**
021 * A fast RNG implementing the {@code XorShift1024*} algorithm.
022 *
023 * <p>Note: This supersedes {@link XorShift1024Star}. The sequences emitted by both
024 * generators are correlated.</p>
025 *
026 * <p>This generator differs only in the final multiplier (a fixed-point representation
027 * of the golden ratio), which eliminates linear dependencies from one of the lowest
028 * bits.</p>
029 *
030 * @see <a href="http://xorshift.di.unimi.it/xorshift1024star.c">Original source code</a>
031 * @see <a href="https://en.wikipedia.org/wiki/Xorshift">Xorshift (Wikipedia)</a>
032 * @since 1.3
033 */
034public class XorShift1024StarPhi extends XorShift1024Star {
035    /**
036     * Creates a new instance.
037     *
038     * @param seed Initial seed.
039     * If the length is larger than 16, only the first 16 elements will
040     * be used; if smaller, the remaining elements will be automatically
041     * set. A seed containing all zeros will create a non-functional generator.
042     */
043    public XorShift1024StarPhi(long[] seed) {
044        super(seed, 0x9e3779b97f4a7c13L);
045    }
046
047    /**
048     * Creates a copy instance.
049     *
050     * @param source Source to copy.
051     */
052    protected XorShift1024StarPhi(XorShift1024StarPhi source) {
053        super(source);
054    }
055
056    /** {@inheritDoc} */
057    @Override
058    protected XorShift1024StarPhi copy() {
059        // This exists to ensure the jump function performed in the super class returns
060        // the correct class type. It should not be public.
061        return new XorShift1024StarPhi(this);
062    }
063}