1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18 package org.apache.commons.math4.legacy.ode;
19
20 import java.util.Random;
21
22 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
23 import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException;
24 import org.apache.commons.math4.legacy.exception.MaxCountExceededException;
25 import org.apache.commons.math4.legacy.exception.NoBracketingException;
26 import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
27 import org.apache.commons.math4.legacy.ode.nonstiff.DormandPrince54Integrator;
28 import org.apache.commons.math4.legacy.ode.nonstiff.DormandPrince853Integrator;
29 import org.apache.commons.math4.legacy.ode.sampling.DummyStepInterpolator;
30 import org.apache.commons.math4.legacy.ode.sampling.StepInterpolator;
31 import org.apache.commons.math4.core.jdkmath.JdkMath;
32 import org.junit.After;
33 import org.junit.Assert;
34 import org.junit.Before;
35 import org.junit.Test;
36
37 public class ContinuousOutputModelTest {
38
39 public ContinuousOutputModelTest() {
40 pb = null;
41 integ = null;
42 }
43
44 @Test
45 public void testBoundaries() throws DimensionMismatchException, NumberIsTooSmallException, MaxCountExceededException, NoBracketingException {
46 integ.addStepHandler(new ContinuousOutputModel());
47 integ.integrate(pb,
48 pb.getInitialTime(), pb.getInitialState(),
49 pb.getFinalTime(), new double[pb.getDimension()]);
50 ContinuousOutputModel cm = (ContinuousOutputModel) integ.getStepHandlers().iterator().next();
51 cm.setInterpolatedTime(2.0 * pb.getInitialTime() - pb.getFinalTime());
52 cm.setInterpolatedTime(2.0 * pb.getFinalTime() - pb.getInitialTime());
53 cm.setInterpolatedTime(0.5 * (pb.getFinalTime() + pb.getInitialTime()));
54 }
55
56 @Test
57 public void testRandomAccess() throws DimensionMismatchException, NumberIsTooSmallException, MaxCountExceededException, NoBracketingException {
58
59 ContinuousOutputModel cm = new ContinuousOutputModel();
60 integ.addStepHandler(cm);
61 integ.integrate(pb,
62 pb.getInitialTime(), pb.getInitialState(),
63 pb.getFinalTime(), new double[pb.getDimension()]);
64
65 Random random = new Random(347588535632L);
66 double maxError = 0.0;
67 double maxErrorDot = 0.0;
68 for (int i = 0; i < 1000; ++i) {
69 double r = random.nextDouble();
70 double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
71 cm.setInterpolatedTime(time);
72 double[] interpolatedY = cm.getInterpolatedState();
73 double[] interpolatedYDot = cm.getInterpolatedDerivatives();
74 double[] theoreticalY = pb.computeTheoreticalState(time);
75 double[] theoreticalYDot = new double[pb.getDimension()];
76 pb.doComputeDerivatives(time, theoreticalY, theoreticalYDot);
77 double dx = interpolatedY[0] - theoreticalY[0];
78 double dy = interpolatedY[1] - theoreticalY[1];
79 double error = dx * dx + dy * dy;
80 maxError = JdkMath.max(maxError, error);
81 double dxDot = interpolatedYDot[0] - theoreticalYDot[0];
82 double dyDot = interpolatedYDot[1] - theoreticalYDot[1];
83 double errorDot = dxDot * dxDot + dyDot * dyDot;
84 maxErrorDot = JdkMath.max(maxErrorDot, errorDot);
85 }
86
87 Assert.assertEquals(0.0, maxError, 1.0e-9);
88 Assert.assertEquals(0.0, maxErrorDot, 4.0e-7);
89 }
90
91 @Test
92 public void testModelsMerging() throws MaxCountExceededException, MathIllegalArgumentException {
93
94
95 FirstOrderDifferentialEquations problem =
96 new FirstOrderDifferentialEquations() {
97 @Override
98 public void computeDerivatives(double t, double[] y, double[] dot) {
99 dot[0] = -y[1];
100 dot[1] = y[0];
101 }
102 @Override
103 public int getDimension() {
104 return 2;
105 }
106 };
107
108
109 ContinuousOutputModel cm1 = new ContinuousOutputModel();
110 FirstOrderIntegrator integ1 =
111 new DormandPrince853Integrator(0, 1.0, 1.0e-8, 1.0e-8);
112 integ1.addStepHandler(cm1);
113 integ1.integrate(problem, JdkMath.PI, new double[] { -1.0, 0.0 },
114 0, new double[2]);
115
116
117 ContinuousOutputModel cm2 = new ContinuousOutputModel();
118 FirstOrderIntegrator integ2 =
119 new DormandPrince853Integrator(0, 0.1, 1.0e-12, 1.0e-12);
120 integ2.addStepHandler(cm2);
121 integ2.integrate(problem, 2.0 * JdkMath.PI, new double[] { 1.0, 0.0 },
122 JdkMath.PI, new double[2]);
123
124
125 ContinuousOutputModel cm = new ContinuousOutputModel();
126 cm.append(cm2);
127 cm.append(new ContinuousOutputModel());
128 cm.append(cm1);
129
130
131 Assert.assertEquals(2.0 * JdkMath.PI, cm.getInitialTime(), 1.0e-12);
132 Assert.assertEquals(0, cm.getFinalTime(), 1.0e-12);
133 Assert.assertEquals(cm.getFinalTime(), cm.getInterpolatedTime(), 1.0e-12);
134 for (double t = 0; t < 2.0 * JdkMath.PI; t += 0.1) {
135 cm.setInterpolatedTime(t);
136 double[] y = cm.getInterpolatedState();
137 Assert.assertEquals(JdkMath.cos(t), y[0], 1.0e-7);
138 Assert.assertEquals(JdkMath.sin(t), y[1], 1.0e-7);
139 }
140 }
141
142 @Test
143 public void testErrorConditions() throws MaxCountExceededException, MathIllegalArgumentException {
144
145 ContinuousOutputModel cm = new ContinuousOutputModel();
146 cm.handleStep(buildInterpolator(0, new double[] { 0.0, 1.0, -2.0 }, 1), true);
147
148
149 Assert.assertTrue(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0 }, 2.0));
150
151
152 Assert.assertTrue(checkAppendError(cm, 10.0, new double[] { 0.0, 1.0, -2.0 }, 20.0));
153
154
155 Assert.assertTrue(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0, -2.0 }, 0.0));
156
157
158 Assert.assertFalse(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0, -2.0 }, 2.0));
159 }
160
161 private boolean checkAppendError(ContinuousOutputModel cm,
162 double t0, double[] y0, double t1)
163 throws MaxCountExceededException, MathIllegalArgumentException {
164 try {
165 ContinuousOutputModel otherCm = new ContinuousOutputModel();
166 otherCm.handleStep(buildInterpolator(t0, y0, t1), true);
167 cm.append(otherCm);
168 } catch(MathIllegalArgumentException iae) {
169 return true;
170 }
171 return false;
172 }
173
174 private StepInterpolator buildInterpolator(double t0, double[] y0, double t1) {
175 DummyStepInterpolator interpolator = new DummyStepInterpolator(y0, new double[y0.length], t1 >= t0);
176 interpolator.storeTime(t0);
177 interpolator.shift();
178 interpolator.storeTime(t1);
179 return interpolator;
180 }
181
182 public void checkValue(double value, double reference) {
183 Assert.assertTrue(JdkMath.abs(value - reference) < 1.0e-10);
184 }
185
186 @Before
187 public void setUp() {
188 pb = new TestProblem3(0.9);
189 double minStep = 0;
190 double maxStep = pb.getFinalTime() - pb.getInitialTime();
191 integ = new DormandPrince54Integrator(minStep, maxStep, 1.0e-8, 1.0e-8);
192 }
193
194 @After
195 public void tearDown() {
196 pb = null;
197 integ = null;
198 }
199
200 private TestProblem3 pb;
201 private FirstOrderIntegrator integ;
202 }