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 import org.apache.commons.math.MathException; 20 21 /** 22 * Base interface for probability distributions. 23 * 24 * @version $Revision: 1054524 $ $Date: 2011-01-03 05:59:18 +0100 (lun. 03 janv. 2011) $ 25 */ 26 public interface Distribution { 27 /** 28 * For a random variable X whose values are distributed according 29 * to this distribution, this method returns P(X ≤ x). In other words, 30 * this method represents the (cumulative) distribution function, or 31 * CDF, for this distribution. 32 * 33 * @param x the value at which the distribution function is evaluated. 34 * @return the probability that a random variable with this 35 * distribution takes a value less than or equal to <code>x</code> 36 * @throws MathException if the cumulative probability can not be 37 * computed due to convergence or other numerical errors. 38 */ 39 double cumulativeProbability(double x) throws MathException; 40 41 /** 42 * For a random variable X whose values are distributed according 43 * to this distribution, this method returns P(x0 ≤ X ≤ x1). 44 * 45 * @param x0 the (inclusive) lower bound 46 * @param x1 the (inclusive) upper bound 47 * @return the probability that a random variable with this distribution 48 * will take a value between <code>x0</code> and <code>x1</code>, 49 * including the endpoints 50 * @throws MathException if the cumulative probability can not be 51 * computed due to convergence or other numerical errors. 52 * @throws IllegalArgumentException if <code>x0 > x1</code> 53 */ 54 double cumulativeProbability(double x0, double x1) throws MathException; 55 56 } 57
