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      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 java.io.Serializable;
     20 
     21 import org.apache.commons.math.MathException;
     22 import org.apache.commons.math.MathRuntimeException;
     23 import org.apache.commons.math.exception.util.LocalizedFormats;
     24 
     25 /**
     26  * Base class for probability distributions.
     27  *
     28  * @version $Revision: 1054524 $ $Date: 2011-01-03 05:59:18 +0100 (lun. 03 janv. 2011) $
     29  */
     30 public abstract class AbstractDistribution
     31     implements Distribution, Serializable {
     32 
     33     /** Serializable version identifier */
     34     private static final long serialVersionUID = -38038050983108802L;
     35 
     36     /**
     37      * Default constructor.
     38      */
     39     protected AbstractDistribution() {
     40         super();
     41     }
     42 
     43     /**
     44      * For a random variable X whose values are distributed according
     45      * to this distribution, this method returns P(x0 ≤ X ≤ x1).
     46      * <p>
     47      * The default implementation uses the identity</p>
     48      * <p>
     49      * P(x0 &le; X &le; x1) = P(X &le; x1) - P(X &le; x0) </p>
     50      *
     51      * @param x0 the (inclusive) lower bound
     52      * @param x1 the (inclusive) upper bound
     53      * @return the probability that a random variable with this distribution
     54      * will take a value between <code>x0</code> and <code>x1</code>,
     55      * including the endpoints.
     56      * @throws MathException if the cumulative probability can not be
     57      * computed due to convergence or other numerical errors.
     58      * @throws IllegalArgumentException if <code>x0 > x1</code>
     59      */
     60     public double cumulativeProbability(double x0, double x1)
     61         throws MathException {
     62         if (x0 > x1) {
     63             throw MathRuntimeException.createIllegalArgumentException(
     64                   LocalizedFormats.LOWER_ENDPOINT_ABOVE_UPPER_ENDPOINT,
     65                   x0, x1);
     66         }
     67         return cumulativeProbability(x1) - cumulativeProbability(x0);
     68     }
     69 }
     70