1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.random; 19 20 /** 21 * This class implements a normalized uniform random generator. 22 * <p>Since it is a normalized random generator, it generates values 23 * from a uniform distribution with mean equal to 0 and standard 24 * deviation equal to 1. Generated values fall in the range 25 * [-√3, +√3].</p> 26 * 27 * @since 1.2 28 * 29 * @version $Revision: 754765 $ $Date: 2009-03-15 17:35:38 -0400 (Sun, 15 Mar 2009) $ 30 */ 31 32 public class UniformRandomGenerator implements NormalizedRandomGenerator { 33 34 /** Serializable version identifier. */ 35 private static final long serialVersionUID = 1569292426375546027L; 36 37 /** Create a new generator. 38 * @param generator underlying random generator to use 39 */ 40 public UniformRandomGenerator(RandomGenerator generator) { 41 this.generator = generator; 42 } 43 44 /** Generate a random scalar with null mean and unit standard deviation. 45 * <p>The number generated is uniformly distributed between -&sqrt;(3) 46 * and +&sqrt;(3).</p> 47 * @return a random scalar with null mean and unit standard deviation 48 */ 49 public double nextNormalizedDouble() { 50 return SQRT3 * (2 * generator.nextDouble() - 1.0); 51 } 52 53 /** Underlying generator. */ 54 private RandomGenerator generator; 55 56 /** Square root of three. */ 57 private static final double SQRT3 = Math.sqrt(3.0); 58 59 }