001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math.ode.nonstiff;
019
020 import static org.junit.Assert.assertEquals;
021 import static org.junit.Assert.assertTrue;
022
023 import java.io.ByteArrayInputStream;
024 import java.io.ByteArrayOutputStream;
025 import java.io.IOException;
026 import java.io.ObjectInputStream;
027 import java.io.ObjectOutputStream;
028 import java.util.Random;
029
030 import org.apache.commons.math.ode.ContinuousOutputModel;
031 import org.apache.commons.math.ode.DerivativeException;
032 import org.apache.commons.math.ode.IntegratorException;
033 import org.apache.commons.math.ode.TestProblem3;
034 import org.apache.commons.math.ode.sampling.StepHandler;
035 import org.apache.commons.math.ode.sampling.StepInterpolator;
036 import org.apache.commons.math.ode.sampling.StepInterpolatorTestUtils;
037 import org.junit.Test;
038
039 public class DormandPrince853StepInterpolatorTest {
040
041 @Test
042 public void derivativesConsistency()
043 throws DerivativeException, IntegratorException {
044 TestProblem3 pb = new TestProblem3(0.1);
045 double minStep = 0;
046 double maxStep = pb.getFinalTime() - pb.getInitialTime();
047 double scalAbsoluteTolerance = 1.0e-8;
048 double scalRelativeTolerance = scalAbsoluteTolerance;
049 DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
050 scalAbsoluteTolerance,
051 scalRelativeTolerance);
052 StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 1.0e-10);
053 }
054
055 @Test
056 public void serialization()
057 throws DerivativeException, IntegratorException,
058 IOException, ClassNotFoundException {
059
060 TestProblem3 pb = new TestProblem3(0.9);
061 double minStep = 0;
062 double maxStep = pb.getFinalTime() - pb.getInitialTime();
063 double scalAbsoluteTolerance = 1.0e-8;
064 double scalRelativeTolerance = scalAbsoluteTolerance;
065 DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
066 scalAbsoluteTolerance,
067 scalRelativeTolerance);
068 integ.addStepHandler(new ContinuousOutputModel());
069 integ.integrate(pb,
070 pb.getInitialTime(), pb.getInitialState(),
071 pb.getFinalTime(), new double[pb.getDimension()]);
072
073 ByteArrayOutputStream bos = new ByteArrayOutputStream();
074 ObjectOutputStream oos = new ObjectOutputStream(bos);
075 for (StepHandler handler : integ.getStepHandlers()) {
076 oos.writeObject(handler);
077 }
078
079 assertTrue(bos.size () > 86000);
080 assertTrue(bos.size () < 87000);
081
082 ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
083 ObjectInputStream ois = new ObjectInputStream(bis);
084 ContinuousOutputModel cm = (ContinuousOutputModel) ois.readObject();
085
086 Random random = new Random(347588535632l);
087 double maxError = 0.0;
088 for (int i = 0; i < 1000; ++i) {
089 double r = random.nextDouble();
090 double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
091 cm.setInterpolatedTime(time);
092 double[] interpolatedY = cm.getInterpolatedState ();
093 double[] theoreticalY = pb.computeTheoreticalState(time);
094 double dx = interpolatedY[0] - theoreticalY[0];
095 double dy = interpolatedY[1] - theoreticalY[1];
096 double error = dx * dx + dy * dy;
097 if (error > maxError) {
098 maxError = error;
099 }
100 }
101
102 assertTrue(maxError < 2.4e-10);
103
104 }
105
106 @Test
107 public void checklone()
108 throws DerivativeException, IntegratorException {
109 TestProblem3 pb = new TestProblem3(0.9);
110 double minStep = 0;
111 double maxStep = pb.getFinalTime() - pb.getInitialTime();
112 double scalAbsoluteTolerance = 1.0e-8;
113 double scalRelativeTolerance = scalAbsoluteTolerance;
114 DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
115 scalAbsoluteTolerance,
116 scalRelativeTolerance);
117 integ.addStepHandler(new StepHandler() {
118 public void handleStep(StepInterpolator interpolator, boolean isLast)
119 throws DerivativeException {
120 StepInterpolator cloned = interpolator.copy();
121 double tA = cloned.getPreviousTime();
122 double tB = cloned.getCurrentTime();
123 double halfStep = Math.abs(tB - tA) / 2;
124 assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
125 assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
126 for (int i = 0; i < 10; ++i) {
127 double t = (i * tB + (9 - i) * tA) / 9;
128 interpolator.setInterpolatedTime(t);
129 assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
130 cloned.setInterpolatedTime(t);
131 assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
132 double[] referenceState = interpolator.getInterpolatedState();
133 double[] cloneState = cloned.getInterpolatedState();
134 for (int j = 0; j < referenceState.length; ++j) {
135 assertEquals(referenceState[j], cloneState[j], 1.0e-12);
136 }
137 }
138 }
139 public boolean requiresDenseOutput() {
140 return true;
141 }
142 public void reset() {
143 }
144 });
145 integ.integrate(pb,
146 pb.getInitialTime(), pb.getInitialState(),
147 pb.getFinalTime(), new double[pb.getDimension()]);
148
149 }
150
151 }