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.math.ode;
19  
20  import junit.framework.*;
21  import java.util.Random;
22  import java.io.ByteArrayOutputStream;
23  import java.io.ByteArrayInputStream;
24  import java.io.ObjectOutputStream;
25  import java.io.ObjectInputStream;
26  import java.io.IOException;
27  
28  import org.apache.commons.math.ode.ContinuousOutputModel;
29  import org.apache.commons.math.ode.DerivativeException;
30  import org.apache.commons.math.ode.DormandPrince54Integrator;
31  import org.apache.commons.math.ode.IntegratorException;
32  
33  public class DormandPrince54StepInterpolatorTest
34    extends TestCase {
35  
36    public DormandPrince54StepInterpolatorTest(String name) {
37      super(name);
38    }
39  
40    public void testSerialization()
41      throws DerivativeException, IntegratorException,
42             IOException, ClassNotFoundException {
43  
44      TestProblem3 pb = new TestProblem3(0.9);
45      double minStep = 0;
46      double maxStep = pb.getFinalTime() - pb.getInitialTime();
47      double scalAbsoluteTolerance = 1.0e-8;
48      double scalRelativeTolerance = scalAbsoluteTolerance;
49      DormandPrince54Integrator integ = new DormandPrince54Integrator(minStep, maxStep,
50                                                                      scalAbsoluteTolerance,
51                                                                      scalRelativeTolerance);
52      integ.setStepHandler(new ContinuousOutputModel());
53      integ.integrate(pb,
54                      pb.getInitialTime(), pb.getInitialState(),
55                      pb.getFinalTime(), new double[pb.getDimension()]);
56  
57      ByteArrayOutputStream bos = new ByteArrayOutputStream();
58      ObjectOutputStream    oos = new ObjectOutputStream(bos);
59      oos.writeObject(integ.getStepHandler());
60  
61      assertTrue(bos.size () > 119500);
62      assertTrue(bos.size () < 120500);
63  
64      ByteArrayInputStream  bis = new ByteArrayInputStream(bos.toByteArray());
65      ObjectInputStream     ois = new ObjectInputStream(bis);
66      ContinuousOutputModel cm  = (ContinuousOutputModel) ois.readObject();
67  
68      Random random = new Random(347588535632l);
69      double maxError = 0.0;
70      for (int i = 0; i < 1000; ++i) {
71        double r = random.nextDouble();
72        double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
73        cm.setInterpolatedTime(time);
74        double[] interpolatedY = cm.getInterpolatedState ();
75        double[] theoreticalY  = pb.computeTheoreticalState(time);
76        double dx = interpolatedY[0] - theoreticalY[0];
77        double dy = interpolatedY[1] - theoreticalY[1];
78        double error = dx * dx + dy * dy;
79        if (error > maxError) {
80          maxError = error;
81        }
82      }
83  
84      assertTrue(maxError < 7.0e-10);
85  
86    }
87  
88    public void testClone()
89      throws DerivativeException, IntegratorException {
90        TestProblem3 pb = new TestProblem3(0.9);
91        double minStep = 0;
92        double maxStep = pb.getFinalTime() - pb.getInitialTime();
93        double scalAbsoluteTolerance = 1.0e-8;
94        double scalRelativeTolerance = scalAbsoluteTolerance;
95        DormandPrince54Integrator integ = new DormandPrince54Integrator(minStep, maxStep,
96                                                                        scalAbsoluteTolerance,
97                                                                        scalRelativeTolerance);
98        integ.setStepHandler(new StepHandler() {
99            public void handleStep(StepInterpolator interpolator, boolean isLast)
100           throws DerivativeException {
101               StepInterpolator cloned = interpolator.copy();
102               double tA = cloned.getPreviousTime();
103               double tB = cloned.getCurrentTime();
104               double halfStep = Math.abs(tB - tA) / 2;
105               assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
106               assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
107               for (int i = 0; i < 10; ++i) {
108                   double t = (i * tB + (9 - i) * tA) / 9;
109                   interpolator.setInterpolatedTime(t);
110                   assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
111                   cloned.setInterpolatedTime(t);
112                   assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
113                   double[] referenceState = interpolator.getInterpolatedState();
114                   double[] cloneState     = cloned.getInterpolatedState();
115                   for (int j = 0; j < referenceState.length; ++j) {
116                       assertEquals(referenceState[j], cloneState[j], 1.0e-12);
117                   }
118               }
119           }
120           public boolean requiresDenseOutput() {
121               return true;
122           }
123           public void reset() {
124           }
125       });
126       integ.integrate(pb,
127               pb.getInitialTime(), pb.getInitialState(),
128               pb.getFinalTime(), new double[pb.getDimension()]);
129 
130   }
131 
132   public static Test suite() {
133     return new TestSuite(DormandPrince54StepInterpolatorTest.class);
134   }
135 
136 }