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
18 package org.apache.commons.math4.legacy.analysis.solvers;
19
20
21 /**
22 * Implements the <em>Illinois</em> method for root-finding (approximating
23 * a zero of a univariate real function). It is a modified
24 * {@link RegulaFalsiSolver <em>Regula Falsi</em>} method.
25 *
26 * <p>Like the <em>Regula Falsi</em> method, convergence is guaranteed by
27 * maintaining a bracketed solution. The <em>Illinois</em> method however,
28 * should converge much faster than the original <em>Regula Falsi</em>
29 * method. Furthermore, this implementation of the <em>Illinois</em> method
30 * should not suffer from the same implementation issues as the <em>Regula
31 * Falsi</em> method, which may fail to convergence in certain cases.</p>
32 *
33 * <p>The <em>Illinois</em> method assumes that the function is continuous,
34 * but not necessarily smooth.</p>
35 *
36 * <p>Implementation based on the following article: M. Dowell and P. Jarratt,
37 * <em>A modified regula falsi method for computing the root of an
38 * equation</em>, BIT Numerical Mathematics, volume 11, number 2,
39 * pages 168-174, Springer, 1971.</p>
40 *
41 * @since 3.0
42 */
43 public class IllinoisSolver extends BaseSecantSolver {
44
45 /** Construct a solver with default accuracy (1e-6). */
46 public IllinoisSolver() {
47 super(DEFAULT_ABSOLUTE_ACCURACY, Method.ILLINOIS);
48 }
49
50 /**
51 * Construct a solver.
52 *
53 * @param absoluteAccuracy Absolute accuracy.
54 */
55 public IllinoisSolver(final double absoluteAccuracy) {
56 super(absoluteAccuracy, Method.ILLINOIS);
57 }
58
59 /**
60 * Construct a solver.
61 *
62 * @param relativeAccuracy Relative accuracy.
63 * @param absoluteAccuracy Absolute accuracy.
64 */
65 public IllinoisSolver(final double relativeAccuracy,
66 final double absoluteAccuracy) {
67 super(relativeAccuracy, absoluteAccuracy, Method.ILLINOIS);
68 }
69
70 /**
71 * Construct a solver.
72 *
73 * @param relativeAccuracy Relative accuracy.
74 * @param absoluteAccuracy Absolute accuracy.
75 * @param functionValueAccuracy Maximum function value error.
76 */
77 public IllinoisSolver(final double relativeAccuracy,
78 final double absoluteAccuracy,
79 final double functionValueAccuracy) {
80 super(relativeAccuracy, absoluteAccuracy, functionValueAccuracy, Method.PEGASUS);
81 }
82 }