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.nonstiff;
19  
20  import static org.junit.Assert.assertTrue;
21  
22  import java.util.Random;
23  import java.io.ByteArrayOutputStream;
24  import java.io.ByteArrayInputStream;
25  import java.io.ObjectOutputStream;
26  import java.io.ObjectInputStream;
27  import java.io.IOException;
28  
29  import org.apache.commons.math.ode.ContinuousOutputModel;
30  import org.apache.commons.math.ode.DerivativeException;
31  import org.apache.commons.math.ode.IntegratorException;
32  import org.apache.commons.math.ode.TestProblem3;
33  import org.apache.commons.math.ode.nonstiff.GillIntegrator;
34  import org.apache.commons.math.ode.sampling.StepHandler;
35  import org.apache.commons.math.ode.sampling.StepInterpolatorTestUtils;
36  import org.junit.Test;
37  
38  public class GillStepInterpolatorTest {
39  
40    @Test
41    public void testDerivativesConsistency()
42    throws DerivativeException, IntegratorException {
43      TestProblem3 pb = new TestProblem3();
44      double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.001;
45      GillIntegrator integ = new GillIntegrator(step);
46      StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 1.0e-10);
47    }
48  
49    @Test
50    public void serialization()
51      throws DerivativeException, IntegratorException,
52             IOException, ClassNotFoundException {
53  
54      TestProblem3 pb = new TestProblem3(0.9);
55      double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.0003;
56      GillIntegrator integ = new GillIntegrator(step);
57      integ.addStepHandler(new ContinuousOutputModel());
58      integ.integrate(pb,
59                      pb.getInitialTime(), pb.getInitialState(),
60                      pb.getFinalTime(), new double[pb.getDimension()]);
61  
62      ByteArrayOutputStream bos = new ByteArrayOutputStream();
63      ObjectOutputStream    oos = new ObjectOutputStream(bos);
64      for (StepHandler handler : integ.getStepHandlers()) {
65          oos.writeObject(handler);
66      }
67  
68      assertTrue(bos.size () > 700000);
69      assertTrue(bos.size () < 701000);
70  
71      ByteArrayInputStream  bis = new ByteArrayInputStream(bos.toByteArray());
72      ObjectInputStream     ois = new ObjectInputStream(bis);
73      ContinuousOutputModel cm  = (ContinuousOutputModel) ois.readObject();
74  
75      Random random = new Random(347588535632l);
76      double maxError = 0.0;
77      for (int i = 0; i < 1000; ++i) {
78        double r = random.nextDouble();
79        double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
80        cm.setInterpolatedTime(time);
81        double[] interpolatedY = cm.getInterpolatedState ();
82        double[] theoreticalY  = pb.computeTheoreticalState(time);
83        double dx = interpolatedY[0] - theoreticalY[0];
84        double dy = interpolatedY[1] - theoreticalY[1];
85        double error = dx * dx + dy * dy;
86        if (error > maxError) {
87          maxError = error;
88        }
89      }
90  
91      assertTrue(maxError < 0.003);
92  
93    }
94  
95  }