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.math3.random;
019
020import org.apache.commons.math3.util.FastMath;
021
022/**
023 * This class implements a normalized uniform random generator.
024 * <p>Since it is a normalized random generator, it generates values
025 * from a uniform distribution with mean equal to 0 and standard
026 * deviation equal to 1. Generated values fall in the range
027 * [-&#x0221A;3, +&#x0221A;3].</p>
028 *
029 * @since 1.2
030 *
031 * @version $Id: UniformRandomGenerator.java 1416643 2012-12-03 19:37:14Z tn $
032 */
033
034public class UniformRandomGenerator implements NormalizedRandomGenerator {
035
036    /** Square root of three. */
037    private static final double SQRT3 = FastMath.sqrt(3.0);
038
039    /** Underlying generator. */
040    private final RandomGenerator generator;
041
042    /** Create a new generator.
043     * @param generator underlying random generator to use
044     */
045    public UniformRandomGenerator(RandomGenerator generator) {
046        this.generator = generator;
047    }
048
049    /** Generate a random scalar with null mean and unit standard deviation.
050     * <p>The number generated is uniformly distributed between -&sqrt;(3)
051     * and +&sqrt;(3).</p>
052     * @return a random scalar with null mean and unit standard deviation
053     */
054    public double nextNormalizedDouble() {
055        return SQRT3 * (2 * generator.nextDouble() - 1.0);
056    }
057
058}