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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.GraggBulirschStoerIntegrator;
31 import org.apache.commons.math.ode.IntegratorException;
32
33 public class GraggBulirschStoerStepInterpolatorTest
34 extends TestCase {
35
36 public GraggBulirschStoerStepInterpolatorTest(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 absTolerance = 1.0e-8;
48 double relTolerance = 1.0e-8;
49
50 GraggBulirschStoerIntegrator integ =
51 new GraggBulirschStoerIntegrator(minStep, maxStep,
52 absTolerance, relTolerance);
53 integ.setStepHandler(new ContinuousOutputModel());
54 integ.integrate(pb,
55 pb.getInitialTime(), pb.getInitialState(),
56 pb.getFinalTime(), new double[pb.getDimension()]);
57
58 ByteArrayOutputStream bos = new ByteArrayOutputStream();
59 ObjectOutputStream oos = new ObjectOutputStream(bos);
60 oos.writeObject(integ.getStepHandler());
61
62 assertTrue(bos.size () > 34000);
63 assertTrue(bos.size () < 35000);
64
65 ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
66 ObjectInputStream ois = new ObjectInputStream(bis);
67 ContinuousOutputModel cm = (ContinuousOutputModel) ois.readObject();
68
69 Random random = new Random(347588535632l);
70 double maxError = 0.0;
71 for (int i = 0; i < 1000; ++i) {
72 double r = random.nextDouble();
73 double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
74 cm.setInterpolatedTime(time);
75 double[] interpolatedY = cm.getInterpolatedState ();
76 double[] theoreticalY = pb.computeTheoreticalState(time);
77 double dx = interpolatedY[0] - theoreticalY[0];
78 double dy = interpolatedY[1] - theoreticalY[1];
79 double error = dx * dx + dy * dy;
80 if (error > maxError) {
81 maxError = error;
82 }
83 }
84
85 assertTrue(maxError < 5.0e-11);
86
87 }
88
89 public void testClone()
90 throws DerivativeException, IntegratorException {
91 TestProblem3 pb = new TestProblem3(0.9);
92 double minStep = 0;
93 double maxStep = pb.getFinalTime() - pb.getInitialTime();
94 double scalAbsoluteTolerance = 1.0e-8;
95 double scalRelativeTolerance = scalAbsoluteTolerance;
96 GraggBulirschStoerIntegrator integ = new GraggBulirschStoerIntegrator(minStep, maxStep,
97 scalAbsoluteTolerance,
98 scalRelativeTolerance);
99 integ.setStepHandler(new StepHandler() {
100 public void handleStep(StepInterpolator interpolator, boolean isLast)
101 throws DerivativeException {
102 StepInterpolator cloned = interpolator.copy();
103 double tA = cloned.getPreviousTime();
104 double tB = cloned.getCurrentTime();
105 double halfStep = Math.abs(tB - tA) / 2;
106 assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
107 assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
108 for (int i = 0; i < 10; ++i) {
109 double t = (i * tB + (9 - i) * tA) / 9;
110 interpolator.setInterpolatedTime(t);
111 assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
112 cloned.setInterpolatedTime(t);
113 assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
114 double[] referenceState = interpolator.getInterpolatedState();
115 double[] cloneState = cloned.getInterpolatedState();
116 for (int j = 0; j < referenceState.length; ++j) {
117 assertEquals(referenceState[j], cloneState[j], 1.0e-12);
118 }
119 }
120 }
121 public boolean requiresDenseOutput() {
122 return true;
123 }
124 public void reset() {
125 }
126 });
127 integ.integrate(pb,
128 pb.getInitialTime(), pb.getInitialState(),
129 pb.getFinalTime(), new double[pb.getDimension()]);
130
131 }
132
133 public static Test suite() {
134 return new TestSuite(GraggBulirschStoerStepInterpolatorTest.class);
135 }
136
137 }