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.analysis.solvers;
18  
19  import org.apache.commons.math.MathException;
20  import org.apache.commons.math.analysis.Expm1Function;
21  import org.apache.commons.math.analysis.QuinticFunction;
22  import org.apache.commons.math.analysis.SinFunction;
23  import org.apache.commons.math.analysis.UnivariateRealFunction;
24  
25  import junit.framework.TestCase;
26  
27  /**
28   * Testcase for Ridders solver.
29   * <p>
30   * Ridders' method converges superlinearly, more specific, its rate of
31   * convergence is sqrt(2). Test runs show that for a default absolute
32   * accuracy of 1E-6, it generally takes less than 5 iterations for close
33   * initial bracket and 5 to 10 iterations for distant initial bracket
34   * to converge.
35   * 
36   * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $ 
37   */
38  public final class RiddersSolverTest extends TestCase {
39  
40      /**
41       * Test the deprecated APIs.
42       */
43      @Deprecated
44      public void testDeprecated() throws MathException {
45          UnivariateRealFunction f = new SinFunction();
46          UnivariateRealSolver solver = new RiddersSolver(f);
47          double min, max, expected, result, tolerance;
48  
49          min = 3.0; max = 4.0; expected = Math.PI;
50          tolerance = Math.max(solver.getAbsoluteAccuracy(),
51                      Math.abs(expected * solver.getRelativeAccuracy()));
52          result = solver.solve(min, max);
53          assertEquals(expected, result, tolerance);
54  
55          min = -1.0; max = 1.5; expected = 0.0;
56          tolerance = Math.max(solver.getAbsoluteAccuracy(),
57                      Math.abs(expected * solver.getRelativeAccuracy()));
58          result = solver.solve(min, max);
59          assertEquals(expected, result, tolerance);
60      }
61  
62      /**
63       * Test of solver for the sine function.
64       */
65      public void testSinFunction() throws MathException {
66          UnivariateRealFunction f = new SinFunction();
67          UnivariateRealSolver solver = new RiddersSolver();
68          double min, max, expected, result, tolerance;
69  
70          min = 3.0; max = 4.0; expected = Math.PI;
71          tolerance = Math.max(solver.getAbsoluteAccuracy(),
72                      Math.abs(expected * solver.getRelativeAccuracy()));
73          result = solver.solve(f, min, max);
74          assertEquals(expected, result, tolerance);
75  
76          min = -1.0; max = 1.5; expected = 0.0;
77          tolerance = Math.max(solver.getAbsoluteAccuracy(),
78                      Math.abs(expected * solver.getRelativeAccuracy()));
79          result = solver.solve(f, min, max);
80          assertEquals(expected, result, tolerance);
81      }
82  
83      /**
84       * Test of solver for the quintic function.
85       */
86      public void testQuinticFunction() throws MathException {
87          UnivariateRealFunction f = new QuinticFunction();
88          UnivariateRealSolver solver = new RiddersSolver();
89          double min, max, expected, result, tolerance;
90  
91          min = -0.4; max = 0.2; expected = 0.0;
92          tolerance = Math.max(solver.getAbsoluteAccuracy(),
93                      Math.abs(expected * solver.getRelativeAccuracy()));
94          result = solver.solve(f, min, max);
95          assertEquals(expected, result, tolerance);
96  
97          min = 0.75; max = 1.5; expected = 1.0;
98          tolerance = Math.max(solver.getAbsoluteAccuracy(),
99                      Math.abs(expected * solver.getRelativeAccuracy()));
100         result = solver.solve(f, min, max);
101         assertEquals(expected, result, tolerance);
102 
103         min = -0.9; max = -0.2; expected = -0.5;
104         tolerance = Math.max(solver.getAbsoluteAccuracy(),
105                     Math.abs(expected * solver.getRelativeAccuracy()));
106         result = solver.solve(f, min, max);
107         assertEquals(expected, result, tolerance);
108     }
109 
110     /**
111      * Test of solver for the exponential function.
112      */
113     public void testExpm1Function() throws MathException {
114         UnivariateRealFunction f = new Expm1Function();
115         UnivariateRealSolver solver = new RiddersSolver();
116         double min, max, expected, result, tolerance;
117 
118         min = -1.0; max = 2.0; expected = 0.0;
119         tolerance = Math.max(solver.getAbsoluteAccuracy(),
120                     Math.abs(expected * solver.getRelativeAccuracy()));
121         result = solver.solve(f, min, max);
122         assertEquals(expected, result, tolerance);
123 
124         min = -20.0; max = 10.0; expected = 0.0;
125         tolerance = Math.max(solver.getAbsoluteAccuracy(),
126                     Math.abs(expected * solver.getRelativeAccuracy()));
127         result = solver.solve(f, min, max);
128         assertEquals(expected, result, tolerance);
129 
130         min = -50.0; max = 100.0; expected = 0.0;
131         tolerance = Math.max(solver.getAbsoluteAccuracy(),
132                     Math.abs(expected * solver.getRelativeAccuracy()));
133         result = solver.solve(f, min, max);
134         assertEquals(expected, result, tolerance);
135     }
136 
137     /**
138      * Test of parameters for the solver.
139      */
140     public void testParameters() throws Exception {
141         UnivariateRealFunction f = new SinFunction();
142         UnivariateRealSolver solver = new RiddersSolver();
143 
144         try {
145             // bad interval
146             solver.solve(f, 1, -1);
147             fail("Expecting IllegalArgumentException - bad interval");
148         } catch (IllegalArgumentException ex) {
149             // expected
150         }
151         try {
152             // no bracketing
153             solver.solve(f, 2, 3);
154             fail("Expecting IllegalArgumentException - no bracketing");
155         } catch (IllegalArgumentException ex) {
156             // expected
157         }
158     }
159 }