Commons Math example source code file (StepInterpolatorTestUtils.java)

This example Commons Math source code file (StepInterpolatorTestUtils.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

derivativeexception, derivativeexception, firstorderintegrator, firstorderintegrator, integratorexception, stephandler, stephandler, stepinterpolatortestutils, testproblemabstract, testproblemabstract

The Commons Math StepInterpolatorTestUtils.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.sampling;

import static org.junit.Assert.assertEquals;

import org.apache.commons.math.ode.DerivativeException;
import org.apache.commons.math.ode.FirstOrderIntegrator;
import org.apache.commons.math.ode.IntegratorException;
import org.apache.commons.math.ode.TestProblemAbstract;

public class StepInterpolatorTestUtils {

    public static void checkDerivativesConsistency(final FirstOrderIntegrator integrator,
                                                   final TestProblemAbstract problem,
                                                   final double threshold)
        throws DerivativeException, IntegratorException {
        integrator.addStepHandler(new StepHandler() {

            public boolean requiresDenseOutput() {
                return true;
            }

            public void handleStep(StepInterpolator interpolator, boolean isLast)
                throws DerivativeException {

                final double h = 0.001 * (interpolator.getCurrentTime() - interpolator.getPreviousTime());
                final double t = interpolator.getCurrentTime() - 300 * h;

                if (Math.abs(h) < 10 * Math.ulp(t)) {
                    return;
                }

                interpolator.setInterpolatedTime(t - 4 * h);
                final double[] yM4h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t - 3 * h);
                final double[] yM3h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t - 2 * h);
                final double[] yM2h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t - h);
                final double[] yM1h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t + h);
                final double[] yP1h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t + 2 * h);
                final double[] yP2h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t + 3 * h);
                final double[] yP3h = interpolator.getInterpolatedState().clone();
                interpolator.setInterpolatedTime(t + 4 * h);
                final double[] yP4h = interpolator.getInterpolatedState().clone();

                interpolator.setInterpolatedTime(t);
                final double[] yDot = interpolator.getInterpolatedDerivatives();

                for (int i = 0; i < yDot.length; ++i) {
                    final double approYDot = ( -3 * (yP4h[i] - yM4h[i]) +
                                               32 * (yP3h[i] - yM3h[i]) +
                                             -168 * (yP2h[i] - yM2h[i]) +
                                              672 * (yP1h[i] - yM1h[i])) / (840 * h);
                    assertEquals(approYDot, yDot[i], threshold);
                }

            }

            public void reset() {
            }

        });

        integrator.integrate(problem,
                             problem.getInitialTime(), problem.getInitialState(),
                             problem.getFinalTime(), new double[problem.getDimension()]);

    }
}