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.distribution;
018    
019    /**
020     * The Pascal distribution.  The Pascal distribution is a special case of the
021     * Negative Binomial distribution where the number of successes parameter is an
022     * integer.
023     * 
024     * There are various ways to express the probability mass and distribution
025     * functions for the Pascal distribution.  The convention employed by the
026     * library is to express these functions in terms of the number of failures in
027     * a Bernoulli experiment [2].
028     *
029     * <p>
030     * References:
031     * <ol>
032     * <li><a href="http://mathworld.wolfram.com/NegativeBinomialDistribution.html">
033     * Negative Binomial Distribution</a></li>
034     * <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>
035     * </ul>
036     * </p>
037     *
038     * @version $Revision: 670469 $ $Date: 2008-06-23 04:01:38 -0400 (Mon, 23 Jun 2008) $
039     * @since 1.2
040     */
041    public interface PascalDistribution extends IntegerDistribution {
042        /**
043         * Access the number of successes for this distribution.
044         * 
045         * @return the number of successes
046         */
047        int getNumberOfSuccesses();
048        
049        /**
050         * Access the probability of success for this distribution.
051         * 
052         * @return the probability of success
053         */
054        double getProbabilityOfSuccess();
055        
056        /**
057         * Change the number of successes for this distribution.
058         * 
059         * @param successes the new number of successes
060         */
061        void setNumberOfSuccesses(int successes);
062        
063        /**
064         * Change the probability of success for this distribution.
065         * 
066         * @param p the new probability of success
067         */
068        void setProbabilityOfSuccess(double p);
069    }