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Java > Open Source Codes > org > apache > commons > math > distribution > TDistributionTest


1 /*
2  * Copyright 2003-2005 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.math.distribution;
17
18 /**
19  * Test cases for TDistribution.
20  * Extends ContinuousDistributionAbstractTest. See class javadoc for
21  * ContinuousDistributionAbstractTest for details.
22  *
23  * @version $Revision$ $Date: 2005-06-26 15:25:41 -0700 (Sun, 26 Jun 2005) $
24  */
25 public class TDistributionTest extends ContinuousDistributionAbstractTest {
26
27     /**
28      * Constructor for TDistributionTest.
29      * @param name
30      */
31     public TDistributionTest(String JavaDoc name) {
32         super(name);
33     }
34
35 //-------------- Implementations for abstract methods -----------------------
36
37     /** Creates the default continuous distribution instance to use in tests. */
38     public ContinuousDistribution makeDistribution() {
39         return DistributionFactory.newInstance().createTDistribution(5.0);
40     }
41
42     /** Creates the default cumulative probability distribution test input values */
43     public double[] makeCumulativeTestPoints() {
44         // quantiles computed using R version 1.8.1 (linux version)
45 return new double[] {-5.89343,-3.36493, -2.570582, -2.015048,
46             -1.475884, 0.0, 5.89343, 3.36493, 2.570582,
47             2.015048, 1.475884};
48     }
49
50     /** Creates the default cumulative probability density test expected values */
51     public double[] makeCumulativeTestValues() {
52         return new double[] {0.001d, 0.01d, 0.025d, 0.05d, 0.1d, 0.5d, 0.999d,
53                 0.990d, 0.975d, 0.950d, 0.900d};
54     }
55
56     // --------------------- Override tolerance --------------
57 protected void setup() throws Exception JavaDoc {
58         super.setUp();
59         setTolerance(1E-6);
60     }
61
62     //---------------------------- Additional test cases -------------------------
63 /**
64      * @see <a HREF="http://issues.apache.org/bugzilla/show_bug.cgi?id=27243">
65      * Bug report that prompted this unit test.</a>
66      */
67     public void testCumulativeProbabilityAgaintStackOverflow() throws Exception JavaDoc {
68         TDistributionImpl td = new TDistributionImpl(5.);
69         double est;
70         est = td.cumulativeProbability(.1);
71         est = td.cumulativeProbability(.01);
72     }
73
74     public void testSmallDf() throws Exception JavaDoc {
75         setDistribution(DistributionFactory.newInstance().createTDistribution(1d));
76         setTolerance(1E-4);
77         // quantiles computed using R version 1.8.1 (linux version)
78 setCumulativeTestPoints(new double[] {-318.3088, -31.82052, -12.70620, -6.313752,
79             -3.077684, 0.0, 318.3088, 31.82052, 12.70620,
80             6.313752, 3.077684});
81         setInverseCumulativeTestValues(getCumulativeTestPoints());
82         verifyCumulativeProbabilities();
83         verifyInverseCumulativeProbabilities();
84     }
85
86     public void testInverseCumulativeProbabilityExtremes() throws Exception JavaDoc {
87         setInverseCumulativeTestPoints(new double[] {0, 1});
88         setInverseCumulativeTestValues(
89                 new double[] {Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY});
90         verifyInverseCumulativeProbabilities();
91     }
92
93     public void testDfAccessors() {
94         TDistribution distribution = (TDistribution) getDistribution();
95         assertEquals(5d, distribution.getDegreesOfFreedom(), Double.MIN_VALUE);
96         distribution.setDegreesOfFreedom(4d);
97         assertEquals(4d, distribution.getDegreesOfFreedom(), Double.MIN_VALUE);
98         try {
99             distribution.setDegreesOfFreedom(0d);
100             fail("Expecting IllegalArgumentException for df = 0");
101         } catch (IllegalArgumentException JavaDoc ex) {
102             // expected
103 }
104     }
105
106 }
107
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