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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.distribution;
19  
20  /**
21   * The Zipf (or zeta) Distribution.
22   * <p>
23   * References:
24   * <ul>
25   * <li><a href="http://mathworld.wolfram.com/ZipfDistribution.html">Zipf 
26   * Distribution</a></li>
27   * </ul>
28   * </p>
29   * 
30   * @version $Revision: 729291 $ $Date: 2008-12-24 05:47:53 -0500 (Wed, 24 Dec 2008) $
31   */
32  public interface ZipfDistribution extends IntegerDistribution {
33      /**
34       * Get the number of elements (e.g. corpus size) for the distribution.
35       * 
36       * @return the number of elements
37       */
38      public int getNumberOfElements();
39  
40      /**
41       * Set the number of elements (e.g. corpus size) for the distribution.
42       * The parameter value must be positive; otherwise an 
43       * <code>IllegalArgumentException</code> is thrown.
44       * 
45       * @param n the number of elements
46       * @throws IllegalArgumentException if n &le; 0
47       */
48      public void setNumberOfElements(int n);
49  
50      /**
51       * Get the exponent characterising the distribution.
52       * 
53       * @return the exponent
54       */
55      public double getExponent();
56  
57      /**
58       * Set the exponent characterising the distribution.
59       * The parameter value must be positive; otherwise an 
60       * <code>IllegalArgumentException</code> is thrown.
61       * 
62       * @param s the exponent
63       * @throws IllegalArgumentException if s &le; 0.0
64       */
65      public void setExponent(double s);
66  }