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18 package org.apache.commons.math.ode.nonstiff;
19
20 import static org.junit.Assert.assertEquals;
21 import static org.junit.Assert.assertTrue;
22
23 import java.io.ByteArrayInputStream;
24 import java.io.ByteArrayOutputStream;
25 import java.io.IOException;
26 import java.io.ObjectInputStream;
27 import java.io.ObjectOutputStream;
28 import java.util.Random;
29
30 import org.apache.commons.math.ode.ContinuousOutputModel;
31 import org.apache.commons.math.ode.DerivativeException;
32 import org.apache.commons.math.ode.IntegratorException;
33 import org.apache.commons.math.ode.TestProblem3;
34 import org.apache.commons.math.ode.sampling.StepHandler;
35 import org.apache.commons.math.ode.sampling.StepInterpolator;
36 import org.apache.commons.math.ode.sampling.StepInterpolatorTestUtils;
37 import org.junit.Test;
38
39 public class GraggBulirschStoerStepInterpolatorTest {
40
41 @Test
42 public void derivativesConsistency()
43 throws DerivativeException, IntegratorException {
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 StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 1.0e-8);
54 }
55
56 @Test
57 public void serialization()
58 throws DerivativeException, IntegratorException,
59 IOException, ClassNotFoundException {
60
61 TestProblem3 pb = new TestProblem3(0.9);
62 double minStep = 0;
63 double maxStep = pb.getFinalTime() - pb.getInitialTime();
64 double absTolerance = 1.0e-8;
65 double relTolerance = 1.0e-8;
66
67 GraggBulirschStoerIntegrator integ =
68 new GraggBulirschStoerIntegrator(minStep, maxStep,
69 absTolerance, relTolerance);
70 integ.addStepHandler(new ContinuousOutputModel());
71 integ.integrate(pb,
72 pb.getInitialTime(), pb.getInitialState(),
73 pb.getFinalTime(), new double[pb.getDimension()]);
74
75 ByteArrayOutputStream bos = new ByteArrayOutputStream();
76 ObjectOutputStream oos = new ObjectOutputStream(bos);
77 for (StepHandler handler : integ.getStepHandlers()) {
78 oos.writeObject(handler);
79 }
80
81 assertTrue(bos.size () > 34000);
82 assertTrue(bos.size () < 35000);
83
84 ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
85 ObjectInputStream ois = new ObjectInputStream(bis);
86 ContinuousOutputModel cm = (ContinuousOutputModel) ois.readObject();
87
88 Random random = new Random(347588535632l);
89 double maxError = 0.0;
90 for (int i = 0; i < 1000; ++i) {
91 double r = random.nextDouble();
92 double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
93 cm.setInterpolatedTime(time);
94 double[] interpolatedY = cm.getInterpolatedState ();
95 double[] theoreticalY = pb.computeTheoreticalState(time);
96 double dx = interpolatedY[0] - theoreticalY[0];
97 double dy = interpolatedY[1] - theoreticalY[1];
98 double error = dx * dx + dy * dy;
99 if (error > maxError) {
100 maxError = error;
101 }
102 }
103
104 assertTrue(maxError < 5.0e-11);
105
106 }
107
108 @Test
109 public void checklone()
110 throws DerivativeException, IntegratorException {
111 TestProblem3 pb = new TestProblem3(0.9);
112 double minStep = 0;
113 double maxStep = pb.getFinalTime() - pb.getInitialTime();
114 double scalAbsoluteTolerance = 1.0e-8;
115 double scalRelativeTolerance = scalAbsoluteTolerance;
116 GraggBulirschStoerIntegrator integ = new GraggBulirschStoerIntegrator(minStep, maxStep,
117 scalAbsoluteTolerance,
118 scalRelativeTolerance);
119 integ.addStepHandler(new StepHandler() {
120 public void handleStep(StepInterpolator interpolator, boolean isLast)
121 throws DerivativeException {
122 StepInterpolator cloned = interpolator.copy();
123 double tA = cloned.getPreviousTime();
124 double tB = cloned.getCurrentTime();
125 double halfStep = Math.abs(tB - tA) / 2;
126 assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
127 assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
128 for (int i = 0; i < 10; ++i) {
129 double t = (i * tB + (9 - i) * tA) / 9;
130 interpolator.setInterpolatedTime(t);
131 assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
132 cloned.setInterpolatedTime(t);
133 assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
134 double[] referenceState = interpolator.getInterpolatedState();
135 double[] cloneState = cloned.getInterpolatedState();
136 for (int j = 0; j < referenceState.length; ++j) {
137 assertEquals(referenceState[j], cloneState[j], 1.0e-12);
138 }
139 }
140 }
141 public boolean requiresDenseOutput() {
142 return true;
143 }
144 public void reset() {
145 }
146 });
147 integ.integrate(pb,
148 pb.getInitialTime(), pb.getInitialState(),
149 pb.getFinalTime(), new double[pb.getDimension()]);
150
151 }
152
153 }