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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  package org.hipparchus.analysis.integration.gauss;
23  
24  import org.hipparchus.analysis.UnivariateFunction;
25  import org.hipparchus.analysis.function.Constant;
26  import org.hipparchus.util.Pair;
27  import org.junit.Assert;
28  import org.junit.Test;
29  
30  /**
31   * Test for {@link GaussIntegrator} class.
32   *
33   */
34  public class GaussIntegratorTest {
35      @Test
36      public void testGetWeights() {
37          final double[] points = { 0, 1.2, 3.4 };
38          final double[] weights = { 9.8, 7.6, 5.4 };
39  
40          final GaussIntegrator integrator
41              = new GaussIntegrator(new Pair<double[], double[]>(points, weights));
42  
43          Assert.assertEquals(weights.length, integrator.getNumberOfPoints());
44  
45          for (int i = 0; i < integrator.getNumberOfPoints(); i++) {
46              Assert.assertEquals(weights[i], integrator.getWeight(i), 0d);
47          }
48      }
49  
50      @Test
51      public void testGetPoints() {
52          final double[] points = { 0, 1.2, 3.4 };
53          final double[] weights = { 9.8, 7.6, 5.4 };
54  
55          final GaussIntegrator integrator
56              = new GaussIntegrator(new Pair<double[], double[]>(points, weights));
57  
58          Assert.assertEquals(points.length, integrator.getNumberOfPoints());
59  
60          for (int i = 0; i < integrator.getNumberOfPoints(); i++) {
61              Assert.assertEquals(points[i], integrator.getPoint(i), 0d);
62          }
63      }
64  
65      @Test
66      public void testIntegrate() {
67          final double[] points = { 0, 1, 2, 3, 4, 5 };
68          final double[] weights = { 1, 1, 1, 1, 1, 1 };
69  
70          final GaussIntegrator integrator
71              = new GaussIntegrator(new Pair<double[], double[]>(points, weights));
72  
73          final double val = 123.456;
74          final UnivariateFunction c = new Constant(val);
75  
76          final double s = integrator.integrate(c);
77          Assert.assertEquals(points.length * val, s, 0d);
78      }
79  }