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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    *      https://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  /*
19   * This is not the original file distributed by the Apache Software Foundation
20   * It has been modified by the Hipparchus project
21   */
22  
23  package org.hipparchus.analysis.solvers;
24  
25  
26  /**
27   * Implements the <em>Illinois</em> method for root-finding (approximating
28   * a zero of a univariate real function). It is a modified
29   * {@link RegulaFalsiSolver <em>Regula Falsi</em>} method.
30   *
31   * <p>Like the <em>Regula Falsi</em> method, convergence is guaranteed by
32   * maintaining a bracketed solution. The <em>Illinois</em> method however,
33   * should converge much faster than the original <em>Regula Falsi</em>
34   * method. Furthermore, this implementation of the <em>Illinois</em> method
35   * should not suffer from the same implementation issues as the <em>Regula
36   * Falsi</em> method, which may fail to convergence in certain cases.</p>
37   *
38   * <p>The <em>Illinois</em> method assumes that the function is continuous,
39   * but not necessarily smooth.</p>
40   *
41   * <p>Implementation based on the following article: M. Dowell and P. Jarratt,
42   * <em>A modified regula falsi method for computing the root of an
43   * equation</em>, BIT Numerical Mathematics, volume 11, number 2,
44   * pages 168-174, Springer, 1971.</p>
45   *
46   */
47  public class IllinoisSolver extends BaseSecantSolver {
48  
49      /** Construct a solver with default accuracy (1e-6). */
50      public IllinoisSolver() {
51          super(DEFAULT_ABSOLUTE_ACCURACY, Method.ILLINOIS);
52      }
53  
54      /**
55       * Construct a solver.
56       *
57       * @param absoluteAccuracy Absolute accuracy.
58       */
59      public IllinoisSolver(final double absoluteAccuracy) {
60          super(absoluteAccuracy, Method.ILLINOIS);
61      }
62  
63      /**
64       * Construct a solver.
65       *
66       * @param relativeAccuracy Relative accuracy.
67       * @param absoluteAccuracy Absolute accuracy.
68       */
69      public IllinoisSolver(final double relativeAccuracy,
70                            final double absoluteAccuracy) {
71          super(relativeAccuracy, absoluteAccuracy, Method.ILLINOIS);
72      }
73  
74      /**
75       * Construct a solver.
76       *
77       * @param relativeAccuracy Relative accuracy.
78       * @param absoluteAccuracy Absolute accuracy.
79       * @param functionValueAccuracy Maximum function value error.
80       */
81      public IllinoisSolver(final double relativeAccuracy,
82                            final double absoluteAccuracy,
83                            final double functionValueAccuracy) {
84          super(relativeAccuracy, absoluteAccuracy, functionValueAccuracy, Method.ILLINOIS);
85      }
86  }