org.apache.commons.math.ode.nonstiff
Class GraggBulirschStoerStepInterpolator

java.lang.Object
  extended by org.apache.commons.math.ode.sampling.AbstractStepInterpolator
      extended by org.apache.commons.math.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
Version:
$Revision: 1061507 $ $Date: 2011-01-20 21:55:00 +0100 (jeu. 20 janv. 2011) $
See Also:
GraggBulirschStoerIntegrator

Field Summary
private  int currentDegree
          Degree of the interpolation polynoms.
private  double[] errfac
          Error coefficients for the interpolation.
private  double[][] polynoms
          Interpolation polynoms.
private static long serialVersionUID
          Serializable version identifier.
private  double[] y0Dot
          Slope at the beginning of the step.
private  double[] y1
          State at the end of the step.
private  double[] y1Dot
          Slope at the end of the step.
private  double[][] yMidDots
          Derivatives at the middle of the step.
 
Fields inherited from class org.apache.commons.math.ode.sampling.AbstractStepInterpolator
currentState, h, interpolatedDerivatives, interpolatedState, interpolatedTime
 
Constructor Summary
GraggBulirschStoerStepInterpolator()
          Simple constructor.
GraggBulirschStoerStepInterpolator(double[] y, double[] y0Dot, double[] y1, double[] y1Dot, double[][] yMidDots, boolean forward)
          Simple constructor.
GraggBulirschStoerStepInterpolator(GraggBulirschStoerStepInterpolator interpolator)
          Copy constructor.
 
Method Summary
 void computeCoefficients(int mu, double h)
          Compute the interpolation coefficients for dense output.
protected  void computeInterpolatedStateAndDerivatives(double theta, double oneMinusThetaH)
          Compute the state and derivatives at the interpolated time.
protected  StepInterpolator doCopy()
          Really copy the finalized instance.
 double estimateError(double[] scale)
          Estimate interpolation error.
 void readExternal(ObjectInput in)
          
private  void resetTables(int maxDegree)
          Reallocate the internal tables.
 void writeExternal(ObjectOutput out)
          
 
Methods inherited from class org.apache.commons.math.ode.sampling.AbstractStepInterpolator
copy, doFinalize, finalizeStep, getCurrentTime, getGlobalCurrentTime, getGlobalPreviousTime, getInterpolatedDerivatives, getInterpolatedState, getInterpolatedTime, getPreviousTime, isForward, readBaseExternal, reinitialize, setInterpolatedTime, setSoftCurrentTime, setSoftPreviousTime, shift, storeTime, writeBaseExternal
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

serialVersionUID

private static final long serialVersionUID
Serializable version identifier.

See Also:
Constant Field Values

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 ...


polynoms

private double[][] polynoms
Interpolation polynoms.


errfac

private double[] errfac
Error coefficients for the interpolation.


currentDegree

private int currentDegree
Degree of the interpolation polynoms.

Constructor Detail

GraggBulirschStoerStepInterpolator

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


GraggBulirschStoerStepInterpolator

public GraggBulirschStoerStepInterpolator(double[] y,
                                          double[] y0Dot,
                                          double[] y1,
                                          double[] y1Dot,
                                          double[][] yMidDots,
                                          boolean forward)
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

GraggBulirschStoerStepInterpolator

public 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 Detail

resetTables

private void resetTables(int maxDegree)
Reallocate the internal tables. Reallocate the internal tables in order to be able to handle interpolation polynoms 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

Specified by:
readExternal in interface Externalizable
Specified by:
readExternal in class AbstractStepInterpolator
Throws:
IOException


Copyright (c) 2003-2013 Apache Software Foundation