fr.cnes.sirius.patrius.math.ode.nonstiff

Class RungeKutta6StepInterpolator

java.lang.Object

fr.cnes.sirius.patrius.math.ode.sampling.AbstractStepInterpolator

fr.cnes.sirius.patrius.math.ode.nonstiff.RungeKutta6StepInterpolator

All Implemented Interfaces:

StepInterpolator, Externalizable, Serializable

public class RungeKutta6StepInterpolator
extends AbstractStepInterpolator

Interpolator for RungeKutta6Integrator.

Warning: This interpolator currently performs a 2nd order interpolation issued from article Dense output for strong stability preserving Runge–Kutta methods, D. Ketcheson, 2016.
Accuracy is however below 1m for standard timestep.

Since:

1.3

Version:

1.3

Author:

Cedric Dental

See Also:

Serialized Form

Concurrency :

not thread-safe

Field Summary

Fields

Modifier and Type	Field and Description
protected AbstractIntegrator	integrator Reference to the integrator.
protected double[]	previousState Previous state.
protected double[][]	yDotK Slopes at the intermediate points

Fields inherited from class fr.cnes.sirius.patrius.math.ode.sampling.AbstractStepInterpolator

currentState, h, interpolatedDerivatives, interpolatedPrimaryDerivatives, interpolatedPrimaryState, interpolatedSecondaryDerivatives, interpolatedSecondaryState, interpolatedState, interpolatedTime

Constructor Summary

Constructors

Constructor and Description
RungeKutta6StepInterpolator(double[] bIn) Simple constructor.
RungeKutta6StepInterpolator(RungeKutta6StepInterpolator interpolator) Copy constructor.

Method Summary

Modifier and Type	Method and 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.
void	readExternal(ObjectInput oi)
void	reinitialize(AbstractIntegrator rkIntegrator, double[] y, double[][] yDotArray, boolean forward, EquationsMapper primaryMapper, EquationsMapper[] secondaryMappers) Reinitialize the instance Some Runge-Kutta integrators need fewer functions evaluations than their counterpart step interpolators.
void	shift() Shift one step forward.
void	writeExternal(ObjectOutput oo)

Methods inherited from class fr.cnes.sirius.patrius.math.ode.sampling.AbstractStepInterpolator

copy, doFinalize, finalizeStep, getCurrentTime, getGlobalCurrentTime, getGlobalPreviousTime, getInterpolatedDerivatives, getInterpolatedSecondaryDerivatives, getInterpolatedSecondaryState, getInterpolatedState, getInterpolatedTime, getPreviousTime, isForward, readBaseExternal, reinitialize, setInterpolatedTime, setSoftCurrentTime, setSoftPreviousTime, storeTime, writeBaseExternal

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

previousState

protected double[] previousState

Previous state.

yDotK

protected double[][] yDotK

Slopes at the intermediate points

integrator

protected AbstractIntegrator integrator

Reference to the integrator.

Constructor Detail

RungeKutta6StepInterpolator

public RungeKutta6StepInterpolator(double[] bIn)

Simple constructor. This constructor builds an instance that is not usable yet, the RungeKuttaStepInterpolator.reinitialize(fr.cnes.sirius.patrius.math.ode.AbstractIntegrator, double[], double[][], boolean, fr.cnes.sirius.patrius.math.ode.EquationsMapper, fr.cnes.sirius.patrius.math.ode.EquationsMapper[]) 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. The RungeKuttaIntegrator class uses the prototyping design pattern to create the step interpolators by cloning an uninitialized model and latter initializing the copy.

Parameters:

bIn - B butcher array

RungeKutta6StepInterpolator

public RungeKutta6StepInterpolator(RungeKutta6StepInterpolator 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

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

reinitialize

public void reinitialize(AbstractIntegrator rkIntegrator,
                         double[] y,
                         double[][] yDotArray,
                         boolean forward,
                         EquationsMapper primaryMapper,
                         EquationsMapper[] secondaryMappers)

Reinitialize the instance

Some Runge-Kutta integrators need fewer functions evaluations than their counterpart step interpolators. So the interpolator should perform the last evaluations they need by themselves. The RungeKuttaIntegrator and EmbeddedRungeKuttaIntegrator abstract classes call this method in order to let the step interpolator perform the evaluations it needs. These evaluations will be performed during the call to doFinalize if any, i.e. only if the step handler either calls the finalizeStep method or the getInterpolatedState method (for an interpolator which needs a finalization) or if it clones the step interpolator.

Parameters:

rkIntegrator - integrator being used

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

yDotArray - reference to the integrator array holding all the intermediate slopes

forward - integration direction indicator

primaryMapper - equations mapper for the primary equations set

secondaryMappers - equations mappers for the secondary equations sets

shift

public void shift()

Shift one step forward. Copy the current time into the previous time, hence preparing the interpolator for future calls to storeTime

Overrides:

shift in class AbstractStepInterpolator

writeExternal

public void writeExternal(ObjectOutput oo)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Specified by:

writeExternal in class AbstractStepInterpolator

Throws:

IOException

readExternal

public void readExternal(ObjectInput oi)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Specified by:

readExternal in class AbstractStepInterpolator

Throws:

IOException

ClassNotFoundException