    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
    018    package org.apache.commons.math3.analysis.solvers;
    019
    020
    021    /**
    022     * Implements the <em>Illinois</em> method for root-finding (approximating
    023     * a zero of a univariate real function). It is a modified
    024     * {@link RegulaFalsiSolver <em>Regula Falsi</em>} method.
    025     *
    026     * <p>Like the <em>Regula Falsi</em> method, convergence is guaranteed by
    027     * maintaining a bracketed solution. The <em>Illinois</em> method however,
    028     * should converge much faster than the original <em>Regula Falsi</em>
    029     * method. Furthermore, this implementation of the <em>Illinois</em> method
    030     * should not suffer from the same implementation issues as the <em>Regula
    031     * Falsi</em> method, which may fail to convergence in certain cases.</p>
    032     *
    033     * <p>The <em>Illinois</em> method assumes that the function is continuous,
    034     * but not necessarily smooth.</p>
    035     *
    036     * <p>Implementation based on the following article: M. Dowell and P. Jarratt,
    037     * <em>A modified regula falsi method for computing the root of an
    038     * equation</em>, BIT Numerical Mathematics, volume 11, number 2,
    039     * pages 168-174, Springer, 1971.</p>
    040     *
    041     * @since 3.0
    042     * @version $Id: IllinoisSolver.java 1364387 2012-07-22 18:14:11Z tn $
    043     */
    044    public class IllinoisSolver extends BaseSecantSolver {
    045
    046        /** Construct a solver with default accuracy (1e-6). */
    047        public IllinoisSolver() {
    048            super(DEFAULT_ABSOLUTE_ACCURACY, Method.ILLINOIS);
    049        }
    050
    051        /**
    052         * Construct a solver.
    053         *
    054         * @param absoluteAccuracy Absolute accuracy.
    055         */
    056        public IllinoisSolver(final double absoluteAccuracy) {
    057            super(absoluteAccuracy, Method.ILLINOIS);
    058        }
    059
    060        /**
    061         * Construct a solver.
    062         *
    063         * @param relativeAccuracy Relative accuracy.
    064         * @param absoluteAccuracy Absolute accuracy.
    065         */
    066        public IllinoisSolver(final double relativeAccuracy,
    067                              final double absoluteAccuracy) {
    068            super(relativeAccuracy, absoluteAccuracy, Method.ILLINOIS);
    069        }
    070
    071        /**
    072         * Construct a solver.
    073         *
    074         * @param relativeAccuracy Relative accuracy.
    075         * @param absoluteAccuracy Absolute accuracy.
    076         * @param functionValueAccuracy Maximum function value error.
    077         */
    078        public IllinoisSolver(final double relativeAccuracy,
    079                              final double absoluteAccuracy,
    080                              final double functionValueAccuracy) {
    081            super(relativeAccuracy, absoluteAccuracy, functionValueAccuracy, Method.PEGASUS);
    082        }
    083    }