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    /**
021     * Base interface for discrete distributions.
022     *
023     * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $
024     */
025    public interface DiscreteDistribution extends Distribution {
026        /**
027         * For a random variable X whose values are distributed according
028         * to this distribution, this method returns P(X = x). In other words, this
029         * method represents the probability mass function, or PMF for the distribution.
030         *
031         * @param x the value at which the probability mass function is evaluated.
032         * @return the value of the probability mass function at x
033         */
034        double probability(double x);
035    }