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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  package org.apache.commons.math.distribution;
18  
19  /**
20   * The Pascal distribution.  The Pascal distribution is a special case of the
21   * Negative Binomial distribution where the number of successes parameter is an
22   * integer.
23   * 
24   * There are various ways to express the probability mass and distribution
25   * functions for the Pascal distribution.  The convention employed by the
26   * library is to express these functions in terms of the number of failures in
27   * a Bernoulli experiment [2].
28   *
29   * <p>
30   * References:
31   * <ol>
32   * <li><a href="http://mathworld.wolfram.com/NegativeBinomialDistribution.html">
33   * Negative Binomial Distribution</a></li>
34   * <oi><a href="http://en.wikipedia.org/wiki/Negative_binomial_distribution#Waiting_time_in_a_Bernoulli_process">Waiting Time in a Bernoulli Process</a></li>
35   * </ul>
36   * </p>
37   *
38   * @version $Revision: 670469 $ $Date: 2008-06-23 04:01:38 -0400 (Mon, 23 Jun 2008) $
39   * @since 1.2
40   */
41  public interface PascalDistribution extends IntegerDistribution {
42      /**
43       * Access the number of successes for this distribution.
44       * 
45       * @return the number of successes
46       */
47      int getNumberOfSuccesses();
48      
49      /**
50       * Access the probability of success for this distribution.
51       * 
52       * @return the probability of success
53       */
54      double getProbabilityOfSuccess();
55      
56      /**
57       * Change the number of successes for this distribution.
58       * 
59       * @param successes the new number of successes
60       */
61      void setNumberOfSuccesses(int successes);
62      
63      /**
64       * Change the probability of success for this distribution.
65       * 
66       * @param p the new probability of success
67       */
68      void setProbabilityOfSuccess(double p);
69  }