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
018 package org.apache.commons.math.random;
019
020 /**
021 * This class implements a normalized uniform random generator.
022 * <p>Since it is a normalized random generator, it generates values
023 * from a uniform distribution with mean equal to 0 and standard
024 * deviation equal to 1. Generated values fall in the range
025 * [-√3, +√3].</p>
026 *
027 * @since 1.2
028 *
029 * @version $Revision: 811827 $ $Date: 2009-09-06 11:32:50 -0400 (Sun, 06 Sep 2009) $
030 */
031
032 public class UniformRandomGenerator implements NormalizedRandomGenerator {
033
034 /** Serializable version identifier. */
035 private static final long serialVersionUID = 1569292426375546027L;
036
037 /** Square root of three. */
038 private static final double SQRT3 = Math.sqrt(3.0);
039
040 /** Underlying generator. */
041 private final RandomGenerator generator;
042
043 /** Create a new generator.
044 * @param generator underlying random generator to use
045 */
046 public UniformRandomGenerator(RandomGenerator generator) {
047 this.generator = generator;
048 }
049
050 /** Generate a random scalar with null mean and unit standard deviation.
051 * <p>The number generated is uniformly distributed between -&sqrt;(3)
052 * and +&sqrt;(3).</p>
053 * @return a random scalar with null mean and unit standard deviation
054 */
055 public double nextNormalizedDouble() {
056 return SQRT3 * (2 * generator.nextDouble() - 1.0);
057 }
058
059 }