    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    import org.apache.commons.math.exception.util.LocalizedFormats;
    024
    025    /**
    026     * Base class for probability distributions.
    027     *
    028     * @version $Revision: 1054524 $ $Date: 2011-01-03 05:59:18 +0100 (lun. 03 janv. 2011) $
    029     */
    030    public abstract class AbstractDistribution
    031        implements Distribution, Serializable {
    032
    033        /** Serializable version identifier */
    034        private static final long serialVersionUID = -38038050983108802L;
    035
    036        /**
    037         * Default constructor.
    038         */
    039        protected AbstractDistribution() {
    040            super();
    041        }
    042
    043        /**
    044         * For a random variable X whose values are distributed according
    045         * to this distribution, this method returns P(x0 &le; X &le; x1).
    046         * <p>
    047         * The default implementation uses the identity</p>
    048         * <p>
    049         * P(x0 &le; X &le; x1) = P(X &le; x1) - P(X &le; x0) </p>
    050         *
    051         * @param x0 the (inclusive) lower bound
    052         * @param x1 the (inclusive) upper bound
    053         * @return the probability that a random variable with this distribution
    054         * will take a value between <code>x0</code> and <code>x1</code>,
    055         * including the endpoints.
    056         * @throws MathException if the cumulative probability can not be
    057         * computed due to convergence or other numerical errors.
    058         * @throws IllegalArgumentException if <code>x0 > x1</code>
    059         */
    060        public double cumulativeProbability(double x0, double x1)
    061            throws MathException {
    062            if (x0 > x1) {
    063                throw MathRuntimeException.createIllegalArgumentException(
    064                      LocalizedFormats.LOWER_ENDPOINT_ABOVE_UPPER_ENDPOINT,
    065                      x0, x1);
    066            }
    067            return cumulativeProbability(x1) - cumulativeProbability(x0);
    068        }
    069    }