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: 670469 $ $Date: 2008-06-23 04:01:38 -0400 (Mon, 23 Jun 2008) $ 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 }