Class GraggBulirschStoerStepInterpolator

java.lang.Object
org.apache.commons.math3.ode.sampling.AbstractStepInterpolator
org.apache.commons.math3.ode.nonstiff.GraggBulirschStoerStepInterpolator
All Implemented Interfaces:
Externalizable, Serializable, StepInterpolator

class GraggBulirschStoerStepInterpolator extends AbstractStepInterpolator
This class implements an interpolator for the Gragg-Bulirsch-Stoer integrator.

This interpolator compute dense output inside the last step produced by a Gragg-Bulirsch-Stoer integrator.

This implementation is basically a reimplementation in Java of the odex fortran code by E. Hairer and G. Wanner. The redistribution policy for this code is available here, for convenience, it is reproduced below.

Copyright (c) 2004, Ernst Hairer
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Since:
1.2
See Also:
  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serializable version identifier.
      See Also:
    • y0Dot

      private double[] y0Dot
      Slope at the beginning of the step.
    • y1

      private double[] y1
      State at the end of the step.
    • y1Dot

      private double[] y1Dot
      Slope at the end of the step.
    • yMidDots

      private double[][] yMidDots
      Derivatives at the middle of the step. element 0 is state at midpoint, element 1 is first derivative ...
    • polynomials

      private double[][] polynomials
      Interpolation polynomials.
    • errfac

      private double[] errfac
      Error coefficients for the interpolation.
    • currentDegree

      private int currentDegree
      Degree of the interpolation polynomials.
  • Constructor Details

    • GraggBulirschStoerStepInterpolator

      public GraggBulirschStoerStepInterpolator()
      Simple constructor. This constructor should not be used directly, it is only intended for the serialization process.
    • GraggBulirschStoerStepInterpolator

      GraggBulirschStoerStepInterpolator(double[] y, double[] y0Dot, double[] y1, double[] y1Dot, double[][] yMidDots, boolean forward, EquationsMapper primaryMapper, EquationsMapper[] secondaryMappers)
      Simple constructor.
      Parameters:
      y - reference to the integrator array holding the current state
      y0Dot - reference to the integrator array holding the slope at the beginning of the step
      y1 - reference to the integrator array holding the state at the end of the step
      y1Dot - reference to the integrator array holding the slope at the end of the step
      yMidDots - reference to the integrator array holding the derivatives at the middle point of the step
      forward - integration direction indicator
      primaryMapper - equations mapper for the primary equations set
      secondaryMappers - equations mappers for the secondary equations sets
    • GraggBulirschStoerStepInterpolator

      GraggBulirschStoerStepInterpolator(GraggBulirschStoerStepInterpolator interpolator)
      Copy constructor.
      Parameters:
      interpolator - interpolator to copy from. The copy is a deep copy: its arrays are separated from the original arrays of the instance
  • Method Details

    • resetTables

      private void resetTables(int maxDegree)
      Reallocate the internal tables. Reallocate the internal tables in order to be able to handle interpolation polynomials up to the given degree
      Parameters:
      maxDegree - maximal degree to handle
    • doCopy

      protected StepInterpolator doCopy()
      Really copy the finalized instance.

      This method is called by AbstractStepInterpolator.copy() after the step has been finalized. It must perform a deep copy to have an new instance completely independent for the original instance.

      Specified by:
      doCopy in class AbstractStepInterpolator
      Returns:
      a copy of the finalized instance
    • computeCoefficients

      public void computeCoefficients(int mu, double h)
      Compute the interpolation coefficients for dense output.
      Parameters:
      mu - degree of the interpolation polynomial
      h - current step
    • estimateError

      public double estimateError(double[] scale)
      Estimate interpolation error.
      Parameters:
      scale - scaling array
      Returns:
      estimate of the interpolation error
    • computeInterpolatedStateAndDerivatives

      protected void computeInterpolatedStateAndDerivatives(double theta, double oneMinusThetaH)
      Compute the state and derivatives at the interpolated time. This is the main processing method that should be implemented by the derived classes to perform the interpolation.
      Specified by:
      computeInterpolatedStateAndDerivatives in class AbstractStepInterpolator
      Parameters:
      theta - normalized interpolation abscissa within the step (theta is zero at the previous time step and one at the current time step)
      oneMinusThetaH - time gap between the interpolated time and the current time
    • writeExternal

      public void writeExternal(ObjectOutput out) throws IOException
      Specified by:
      writeExternal in interface Externalizable
      Specified by:
      writeExternal in class AbstractStepInterpolator
      Throws:
      IOException
    • readExternal

      public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
      Specified by:
      readExternal in interface Externalizable
      Specified by:
      readExternal in class AbstractStepInterpolator
      Throws:
      IOException
      ClassNotFoundException