Package org.apache.commons.math.ode.sampling

Class NordsieckStepInterpolator

java.lang.Object

org.apache.commons.math.ode.sampling.AbstractStepInterpolator

org.apache.commons.math.ode.sampling.NordsieckStepInterpolator

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, StepInterpolator

public class NordsieckStepInterpolator
extends AbstractStepInterpolator

This class implements an interpolator for integrators using Nordsieck representation.

This interpolator computes dense output around the current point. The interpolation equation is based on Taylor series formulas.

Since:

2.0

Version:

$Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $

See Also:

AdamsBashforthIntegrator, AdamsMoultonIntegrator, Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected double[]	stateVariation	State variation.

Fields inherited from class org.apache.commons.math.ode.sampling.AbstractStepInterpolator

currentState, h, interpolatedDerivatives, interpolatedState, interpolatedTime

Constructor Summary

Constructors

Constructor	Description
NordsieckStepInterpolator()	Simple constructor.
NordsieckStepInterpolator(NordsieckStepInterpolator interpolator)	Copy constructor.

Method Summary

Modifier and Type	Method	Description
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[]	getInterpolatedStateVariation()	Get the state vector variation from current to interpolated state.
void	readExternal(java.io.ObjectInput in)
void	reinitialize(double[] y, boolean forward)	Reinitialize the instance.
void	reinitialize(double time, double stepSize, double[] scaledDerivative, Array2DRowRealMatrix nordsieckVector)	Reinitialize the instance.
void	rescale(double stepSize)	Rescale the instance.
void	writeExternal(java.io.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, 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

stateVariation

protected double[] stateVariation

State variation.

Constructor Detail

NordsieckStepInterpolator

public NordsieckStepInterpolator()

Simple constructor. This constructor builds an instance that is not usable yet, the AbstractStepInterpolator.reinitialize(double[], boolean) method should be called before using the instance in order to initialize the internal arrays. This constructor is used only in order to delay the initialization in some cases.

NordsieckStepInterpolator

public NordsieckStepInterpolator(NordsieckStepInterpolator 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

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

reinitialize

public void reinitialize(double[] y,
                         boolean forward)

Reinitialize the instance.

Beware that all arrays must be references to integrator arrays, in order to ensure proper update without copy.

Overrides:

reinitialize in class AbstractStepInterpolator

Parameters:

y - reference to the integrator array holding the state at the end of the step

forward - integration direction indicator

reinitialize

public void reinitialize(double time,
                         double stepSize,
                         double[] scaledDerivative,
                         Array2DRowRealMatrix nordsieckVector)

Reinitialize the instance.

Beware that all arrays must be references to integrator arrays, in order to ensure proper update without copy.

Parameters:

time - time at which all arrays are defined

stepSize - step size used in the scaled and nordsieck arrays

scaledDerivative - reference to the integrator array holding the first scaled derivative

nordsieckVector - reference to the integrator matrix holding the nordsieck vector

rescale

public void rescale(double stepSize)

Rescale the instance.

Since the scaled and Nordiseck arrays are shared with the caller, this method has the side effect of rescaling this arrays in the caller too.

Parameters:

stepSize - new step size to use in the scaled and nordsieck arrays

getInterpolatedStateVariation

public double[] getInterpolatedStateVariation()
                                       throws DerivativeException

Get the state vector variation from current to interpolated state.

This method is aimed at computing y(t_{interpolation}) -y(t_current) accurately by avoiding the cancellation errors that would occur if the subtraction were performed explicitly.

The returned vector is a reference to a reused array, so it should not be modified and it should be copied if it needs to be preserved across several calls.

Returns:

state vector at time AbstractStepInterpolator.getInterpolatedTime()

Throws:

DerivativeException - if this call induces an automatic step finalization that throws one

See Also:

AbstractStepInterpolator.getInterpolatedDerivatives()

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(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Specified by:

writeExternal in class AbstractStepInterpolator

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Specified by:

readExternal in class AbstractStepInterpolator

Throws:

java.io.IOException

java.lang.ClassNotFoundException