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 }