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.distribution;
019    
020    /**
021     * The Zipf (or zeta) Distribution.
022     * <p>
023     * References:
024     * <ul>
025     * <li><a href="http://mathworld.wolfram.com/ZipfDistribution.html">Zipf 
026     * Distribution</a></li>
027     * </ul>
028     * </p>
029     * 
030     * @version $Revision: 729291 $ $Date: 2008-12-24 05:47:53 -0500 (Wed, 24 Dec 2008) $
031     */
032    public interface ZipfDistribution extends IntegerDistribution {
033        /**
034         * Get the number of elements (e.g. corpus size) for the distribution.
035         * 
036         * @return the number of elements
037         */
038        public int getNumberOfElements();
039    
040        /**
041         * Set the number of elements (e.g. corpus size) for the distribution.
042         * The parameter value must be positive; otherwise an 
043         * <code>IllegalArgumentException</code> is thrown.
044         * 
045         * @param n the number of elements
046         * @throws IllegalArgumentException if n &le; 0
047         */
048        public void setNumberOfElements(int n);
049    
050        /**
051         * Get the exponent characterising the distribution.
052         * 
053         * @return the exponent
054         */
055        public double getExponent();
056    
057        /**
058         * Set the exponent characterising the distribution.
059         * The parameter value must be positive; otherwise an 
060         * <code>IllegalArgumentException</code> is thrown.
061         * 
062         * @param s the exponent
063         * @throws IllegalArgumentException if s &le; 0.0
064         */
065        public void setExponent(double s);
066    }