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Commons Math example source code file (GraggBulirschStoerStepInterpolatorTest.java)

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

Java - Commons Math tags/keywords

bytearrayoutputstream, continuousoutputmodel, derivativeexception, derivativeexception, graggbulirschstoerintegrator, graggbulirschstoerintegrator, integratorexception, io, objectoutputstream, random, stephandler, test, test, testproblem3, testproblem3, util

The Commons Math GraggBulirschStoerStepInterpolatorTest.java 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.math.ode.nonstiff;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

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.math.ode.ContinuousOutputModel;
import org.apache.commons.math.ode.DerivativeException;
import org.apache.commons.math.ode.IntegratorException;
import org.apache.commons.math.ode.TestProblem3;
import org.apache.commons.math.ode.sampling.StepHandler;
import org.apache.commons.math.ode.sampling.StepInterpolator;
import org.apache.commons.math.ode.sampling.StepInterpolatorTestUtils;
import org.junit.Test;

public class GraggBulirschStoerStepInterpolatorTest {

  @Test
  public void derivativesConsistency()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3(0.9);
    double minStep   = 0;
    double maxStep   = pb.getFinalTime() - pb.getInitialTime();
    double absTolerance = 1.0e-8;
    double relTolerance = 1.0e-8;

    GraggBulirschStoerIntegrator integ =
      new GraggBulirschStoerIntegrator(minStep, maxStep,
                                       absTolerance, relTolerance);
    StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 1.0e-8);
  }

  @Test
  public void serialization()
    throws DerivativeException, IntegratorException,
           IOException, ClassNotFoundException {

    TestProblem3 pb  = new TestProblem3(0.9);
    double minStep   = 0;
    double maxStep   = pb.getFinalTime() - pb.getInitialTime();
    double absTolerance = 1.0e-8;
    double relTolerance = 1.0e-8;

    GraggBulirschStoerIntegrator integ =
      new GraggBulirschStoerIntegrator(minStep, maxStep,
                                       absTolerance, relTolerance);
    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);
    }

    assertTrue(bos.size () > 33000);
    assertTrue(bos.size () < 34000);

    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;
      }
    }

    assertTrue(maxError < 5.0e-10);

  }

  @Test
  public void checklone()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;
    GraggBulirschStoerIntegrator integ = new GraggBulirschStoerIntegrator(minStep, maxStep,
                                                                          scalAbsoluteTolerance,
                                                                          scalRelativeTolerance);
    integ.addStepHandler(new StepHandler() {
        public void handleStep(StepInterpolator interpolator, boolean isLast)
        throws DerivativeException {
            StepInterpolator cloned = interpolator.copy();
            double tA = cloned.getPreviousTime();
            double tB = cloned.getCurrentTime();
            double halfStep = Math.abs(tB - tA) / 2;
            assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
            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);
                assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
                cloned.setInterpolatedTime(t);
                assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
                double[] referenceState = interpolator.getInterpolatedState();
                double[] cloneState     = cloned.getInterpolatedState();
                for (int j = 0; j < referenceState.length; ++j) {
                    assertEquals(referenceState[j], cloneState[j], 1.0e-12);
                }
            }
        }
        public boolean requiresDenseOutput() {
            return true;
        }
        public void reset() {
        }
    });
    integ.integrate(pb,
            pb.getInitialTime(), pb.getInitialState(),
            pb.getFinalTime(), new double[pb.getDimension()]);

  }

}

Other Commons Math examples (source code examples)

Here is a short list of links related to this Commons Math GraggBulirschStoerStepInterpolatorTest.java source code file:

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