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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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
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package org.apache.commons.math.ode;
import junit.framework.*;
import java.util.Random;
import org.apache.commons.math.ode.DerivativeException;
import org.apache.commons.math.ode.ContinuousOutputModel;
import org.apache.commons.math.ode.FirstOrderIntegrator;
import org.apache.commons.math.ode.IntegratorException;
import org.apache.commons.math.ode.nonstiff.DormandPrince54Integrator;
import org.apache.commons.math.ode.nonstiff.DormandPrince853Integrator;
import org.apache.commons.math.ode.sampling.DummyStepInterpolator;
import org.apache.commons.math.ode.sampling.StepInterpolator;
import org.apache.commons.math.util.FastMath;
public class ContinuousOutputModelTest
extends TestCase {
public ContinuousOutputModelTest(String name) {
super(name);
pb = null;
integ = null;
}
public void testBoundaries()
throws DerivativeException, IntegratorException {
integ.addStepHandler(new ContinuousOutputModel());
integ.integrate(pb,
pb.getInitialTime(), pb.getInitialState(),
pb.getFinalTime(), new double[pb.getDimension()]);
ContinuousOutputModel cm = (ContinuousOutputModel) integ.getStepHandlers().iterator().next();
cm.setInterpolatedTime(2.0 * pb.getInitialTime() - pb.getFinalTime());
cm.setInterpolatedTime(2.0 * pb.getFinalTime() - pb.getInitialTime());
cm.setInterpolatedTime(0.5 * (pb.getFinalTime() + pb.getInitialTime()));
}
public void testRandomAccess()
throws DerivativeException, IntegratorException {
ContinuousOutputModel cm = new ContinuousOutputModel();
integ.addStepHandler(cm);
integ.integrate(pb,
pb.getInitialTime(), pb.getInitialState(),
pb.getFinalTime(), new double[pb.getDimension()]);
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;
}
}
assertTrue(maxError < 1.0e-9);
}
public void testModelsMerging()
throws DerivativeException, IntegratorException {
// theoretical solution: y[0] = cos(t), y[1] = sin(t)
FirstOrderDifferentialEquations problem =
new FirstOrderDifferentialEquations() {
private static final long serialVersionUID = 2472449657345878299L;
public void computeDerivatives(double t, double[] y, double[] dot)
throws DerivativeException {
dot[0] = -y[1];
dot[1] = y[0];
}
public int getDimension() {
return 2;
}
};
// integrate backward from π to 0;
ContinuousOutputModel cm1 = new ContinuousOutputModel();
FirstOrderIntegrator integ1 =
new DormandPrince853Integrator(0, 1.0, 1.0e-8, 1.0e-8);
integ1.addStepHandler(cm1);
integ1.integrate(problem, FastMath.PI, new double[] { -1.0, 0.0 },
0, new double[2]);
// integrate backward from 2π to π
ContinuousOutputModel cm2 = new ContinuousOutputModel();
FirstOrderIntegrator integ2 =
new DormandPrince853Integrator(0, 0.1, 1.0e-12, 1.0e-12);
integ2.addStepHandler(cm2);
integ2.integrate(problem, 2.0 * FastMath.PI, new double[] { 1.0, 0.0 },
FastMath.PI, new double[2]);
// merge the two half circles
ContinuousOutputModel cm = new ContinuousOutputModel();
cm.append(cm2);
cm.append(new ContinuousOutputModel());
cm.append(cm1);
// check circle
assertEquals(2.0 * FastMath.PI, cm.getInitialTime(), 1.0e-12);
assertEquals(0, cm.getFinalTime(), 1.0e-12);
assertEquals(cm.getFinalTime(), cm.getInterpolatedTime(), 1.0e-12);
for (double t = 0; t < 2.0 * FastMath.PI; t += 0.1) {
cm.setInterpolatedTime(t);
double[] y = cm.getInterpolatedState();
assertEquals(FastMath.cos(t), y[0], 1.0e-7);
assertEquals(FastMath.sin(t), y[1], 1.0e-7);
}
}
public void testErrorConditions()
throws DerivativeException {
ContinuousOutputModel cm = new ContinuousOutputModel();
cm.handleStep(buildInterpolator(0, new double[] { 0.0, 1.0, -2.0 }, 1), true);
// dimension mismatch
assertTrue(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0 }, 2.0));
// hole between time ranges
assertTrue(checkAppendError(cm, 10.0, new double[] { 0.0, 1.0, -2.0 }, 20.0));
// propagation direction mismatch
assertTrue(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0, -2.0 }, 0.0));
// no errors
assertFalse(checkAppendError(cm, 1.0, new double[] { 0.0, 1.0, -2.0 }, 2.0));
}
private boolean checkAppendError(ContinuousOutputModel cm,
double t0, double[] y0, double t1)
throws DerivativeException {
try {
ContinuousOutputModel otherCm = new ContinuousOutputModel();
otherCm.handleStep(buildInterpolator(t0, y0, t1), true);
cm.append(otherCm);
} catch(IllegalArgumentException iae) {
return true; // there was an allowable error
}
return false; // no allowable error
}
private StepInterpolator buildInterpolator(double t0, double[] y0, double t1) {
DummyStepInterpolator interpolator = new DummyStepInterpolator(y0, new double[y0.length], t1 >= t0);
interpolator.storeTime(t0);
interpolator.shift();
interpolator.storeTime(t1);
return interpolator;
}
public void checkValue(double value, double reference) {
assertTrue(FastMath.abs(value - reference) < 1.0e-10);
}
@Override
public void setUp() {
pb = new TestProblem3(0.9);
double minStep = 0;
double maxStep = pb.getFinalTime() - pb.getInitialTime();
integ = new DormandPrince54Integrator(minStep, maxStep, 1.0e-8, 1.0e-8);
}
@Override
public void tearDown() {
pb = null;
integ = null;
}
TestProblem3 pb;
FirstOrderIntegrator integ;
}