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: 754765 $ $Date: 2009-03-15 17:35:38 -0400 (Sun, 15 Mar 2009) $ 030 */ 031 032 public class UniformRandomGenerator implements NormalizedRandomGenerator { 033 034 /** Serializable version identifier. */ 035 private static final long serialVersionUID = 1569292426375546027L; 036 037 /** Create a new generator. 038 * @param generator underlying random generator to use 039 */ 040 public UniformRandomGenerator(RandomGenerator generator) { 041 this.generator = generator; 042 } 043 044 /** Generate a random scalar with null mean and unit standard deviation. 045 * <p>The number generated is uniformly distributed between -&sqrt;(3) 046 * and +&sqrt;(3).</p> 047 * @return a random scalar with null mean and unit standard deviation 048 */ 049 public double nextNormalizedDouble() { 050 return SQRT3 * (2 * generator.nextDouble() - 1.0); 051 } 052 053 /** Underlying generator. */ 054 private RandomGenerator generator; 055 056 /** Square root of three. */ 057 private static final double SQRT3 = Math.sqrt(3.0); 058 059 }