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    package org.apache.commons.math.stat.descriptive.rank;
018    
019    import java.io.Serializable;
020    
021    
022    /**
023     * Returns the median of the available values.  This is the same as the 50th percentile.
024     * See {@link Percentile} for a description of the algorithm used.
025     * <p>
026     * <strong>Note that this implementation is not synchronized.</strong> If 
027     * multiple threads access an instance of this class concurrently, and at least
028     * one of the threads invokes the <code>increment()</code> or 
029     * <code>clear()</code> method, it must be synchronized externally.</p>
030     * 
031     * @version $Revision: 720030 $ $Date: 2008-11-23 13:47:50 -0500 (Sun, 23 Nov 2008) $
032     */
033    public class Median extends Percentile implements Serializable {
034    
035        /** Serializable version identifier */
036        private static final long serialVersionUID = -3961477041290915687L;    
037    
038        /**
039         * Default constructor.
040         */
041        public Median() {
042            super(50.0);
043        }
044        
045        /**
046         * Copy constructor, creates a new {@code Median} identical
047         * to the {@code original}
048         * 
049         * @param original the {@code Median} instance to copy
050         */
051        public Median(Median original) {
052            super(original);
053        }        
054    
055    }