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 */
032
033public class UniformRandomGenerator implements NormalizedRandomGenerator {
034
035    /** Square root of three. */
036    private static final double SQRT3 = FastMath.sqrt(3.0);
037
038    /** Underlying generator. */
039    private final RandomGenerator generator;
040
041    /** Create a new generator.
042     * @param generator underlying random generator to use
043     */
044    public UniformRandomGenerator(RandomGenerator generator) {
045        this.generator = generator;
046    }
047
048    /** Generate a random scalar with null mean and unit standard deviation.
049     * <p>The number generated is uniformly distributed between -&sqrt;(3)
050     * and +&sqrt;(3).</p>
051     * @return a random scalar with null mean and unit standard deviation
052     */
053    public double nextNormalizedDouble() {
054        return SQRT3 * (2 * generator.nextDouble() - 1.0);
055    }
056
057}