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 import java.io.Serializable; 020 021 import org.apache.commons.math.MathException; 022 import org.apache.commons.math.MathRuntimeException; 023 024 /** 025 * Base class for probability distributions. 026 * 027 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $ 028 */ 029 public abstract class AbstractDistribution 030 implements Distribution, Serializable { 031 032 /** Serializable version identifier */ 033 private static final long serialVersionUID = -38038050983108802L; 034 035 /** 036 * Default constructor. 037 */ 038 protected AbstractDistribution() { 039 super(); 040 } 041 042 /** 043 * For a random variable X whose values are distributed according 044 * to this distribution, this method returns P(x0 ≤ X ≤ x1). 045 * <p> 046 * The default implementation uses the identity</p> 047 * <p> 048 * P(x0 ≤ X ≤ x1) = P(X ≤ x1) - P(X ≤ x0) </p> 049 * 050 * @param x0 the (inclusive) lower bound 051 * @param x1 the (inclusive) upper bound 052 * @return the probability that a random variable with this distribution 053 * will take a value between <code>x0</code> and <code>x1</code>, 054 * including the endpoints. 055 * @throws MathException if the cumulative probability can not be 056 * computed due to convergence or other numerical errors. 057 * @throws IllegalArgumentException if <code>x0 > x1</code> 058 */ 059 public double cumulativeProbability(double x0, double x1) 060 throws MathException { 061 if (x0 > x1) { 062 throw MathRuntimeException.createIllegalArgumentException( 063 "lower endpoint ({0}) must be less than or equal to upper endpoint ({1})", 064 x0, x1); 065 } 066 return cumulativeProbability(x1) - cumulativeProbability(x0); 067 } 068 }