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* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
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package org.apache.commons.math4.ode.nonstiff;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Random;
import org.apache.commons.math4.exception.DimensionMismatchException;
import org.apache.commons.math4.exception.MaxCountExceededException;
import org.apache.commons.math4.exception.NoBracketingException;
import org.apache.commons.math4.exception.NumberIsTooSmallException;
import org.apache.commons.math4.ode.ContinuousOutputModel;
import org.apache.commons.math4.ode.TestProblem3;
import org.apache.commons.math4.ode.nonstiff.DormandPrince853Integrator;
import org.apache.commons.math4.ode.sampling.StepHandler;
import org.apache.commons.math4.ode.sampling.StepInterpolator;
import org.apache.commons.math4.ode.sampling.StepInterpolatorTestUtils;
import org.apache.commons.math4.util.FastMath;
import org.junit.Assert;
import org.junit.Test;
public class DormandPrince853StepInterpolatorTest {
@Test
public void derivativesConsistency()
throws DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
TestProblem3 pb = new TestProblem3(0.1);
double minStep = 0;
double maxStep = pb.getFinalTime() - pb.getInitialTime();
double scalAbsoluteTolerance = 1.0e-8;
double scalRelativeTolerance = scalAbsoluteTolerance;
DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
scalAbsoluteTolerance,
scalRelativeTolerance);
StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 0.01, 1.8e-12);
}
@Test
public void serialization()
throws IOException, ClassNotFoundException,
DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
TestProblem3 pb = new TestProblem3(0.9);
double minStep = 0;
double maxStep = pb.getFinalTime() - pb.getInitialTime();
double scalAbsoluteTolerance = 1.0e-8;
double scalRelativeTolerance = scalAbsoluteTolerance;
DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
scalAbsoluteTolerance,
scalRelativeTolerance);
integ.addStepHandler(new ContinuousOutputModel());
integ.integrate(pb,
pb.getInitialTime(), pb.getInitialState(),
pb.getFinalTime(), new double[pb.getDimension()]);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
for (StepHandler handler : integ.getStepHandlers()) {
oos.writeObject(handler);
}
Assert.assertTrue(bos.size () > 90000);
Assert.assertTrue(bos.size () < 100000);
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
ContinuousOutputModel cm = (ContinuousOutputModel) ois.readObject();
Random random = new Random(347588535632l);
double maxError = 0.0;
for (int i = 0; i < 1000; ++i) {
double r = random.nextDouble();
double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
cm.setInterpolatedTime(time);
double[] interpolatedY = cm.getInterpolatedState ();
double[] theoreticalY = pb.computeTheoreticalState(time);
double dx = interpolatedY[0] - theoreticalY[0];
double dy = interpolatedY[1] - theoreticalY[1];
double error = dx * dx + dy * dy;
if (error > maxError) {
maxError = error;
}
}
Assert.assertTrue(maxError < 2.4e-10);
}
@Test
public void checklone()
throws DimensionMismatchException, NumberIsTooSmallException,
MaxCountExceededException, NoBracketingException {
TestProblem3 pb = new TestProblem3(0.9);
double minStep = 0;
double maxStep = pb.getFinalTime() - pb.getInitialTime();
double scalAbsoluteTolerance = 1.0e-8;
double scalRelativeTolerance = scalAbsoluteTolerance;
DormandPrince853Integrator integ = new DormandPrince853Integrator(minStep, maxStep,
scalAbsoluteTolerance,
scalRelativeTolerance);
integ.addStepHandler(new StepHandler() {
@Override
public void handleStep(StepInterpolator interpolator, boolean isLast)
throws MaxCountExceededException {
StepInterpolator cloned = interpolator.copy();
double tA = cloned.getPreviousTime();
double tB = cloned.getCurrentTime();
double halfStep = FastMath.abs(tB - tA) / 2;
Assert.assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
Assert.assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
for (int i = 0; i < 10; ++i) {
double t = (i * tB + (9 - i) * tA) / 9;
interpolator.setInterpolatedTime(t);
Assert.assertTrue(FastMath.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
cloned.setInterpolatedTime(t);
Assert.assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
double[] referenceState = interpolator.getInterpolatedState();
double[] cloneState = cloned.getInterpolatedState();
for (int j = 0; j < referenceState.length; ++j) {
Assert.assertEquals(referenceState[j], cloneState[j], 1.0e-12);
}
}
}
@Override
public void init(double t0, double[] y0, double t) {
}
});
integ.integrate(pb,
pb.getInitialTime(), pb.getInitialState(),
pb.getFinalTime(), new double[pb.getDimension()]);
}
}