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Java example source code file (DormandPrince853StepInterpolatorTest.java)

This example Java source code file (DormandPrince853StepInterpolatorTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytearrayoutputstream, continuousoutputmodel, dimensionmismatchexception, dormandprince853integrator, ioexception, maxcountexceededexception, nobracketingexception, numberistoosmallexception, objectinputstream, objectoutputstream, random, stephandler, stepinterpolator, testproblem3, util

The DormandPrince853StepInterpolatorTest.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * 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
 * limitations under the License.
 */

package org.apache.commons.math3.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.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.MaxCountExceededException;
import org.apache.commons.math3.exception.NoBracketingException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.ode.ContinuousOutputModel;
import org.apache.commons.math3.ode.TestProblem3;
import org.apache.commons.math3.ode.sampling.StepHandler;
import org.apache.commons.math3.ode.sampling.StepInterpolator;
import org.apache.commons.math3.ode.sampling.StepInterpolatorTestUtils;
import org.apache.commons.math3.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() {
        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);
                }
            }
        }
        public void init(double t0, double[] y0, double t) {
        }
    });
    integ.integrate(pb,
            pb.getInitialTime(), pb.getInitialState(),
            pb.getFinalTime(), new double[pb.getDimension()]);

  }

}

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