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     * [-&#x0221A;3, +&#x0221A;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    }