Package nl.tudelft.simulation.jstats.ode.integrators

Class CachingNumericalIntegrator

java.lang.Object

nl.tudelft.simulation.jstats.ode.integrators.NumericalIntegrator

nl.tudelft.simulation.jstats.ode.integrators.CachingNumericalIntegrator

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

Adams, Milne

public abstract class CachingNumericalIntegrator
extends NumericalIntegrator

The CachingNumericalIntegrator is the basis for an integrator that needs access to previously calculated values of y', e.g. y'_(k-1), y'_(k-2), etc.

Copyright (c) 2002-2024 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://simulation.tudelft.nl. The DSOL project is distributed under a three-clause BSD-style license, which can be found at https://https://simulation.tudelft.nl/dsol/docs/latest/license.html.

Author:

Alexander Verbraeck

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected NumericalIntegrator	startingIntegrator	The primer integrator.
protected int	startingSubSteps	the substeps to use when starting the integrator.

Fields inherited from class nl.tudelft.simulation.jstats.ode.integrators.NumericalIntegrator

equation, error, stepSize

Constructor Summary

Constructors

Constructor	Description
CachingNumericalIntegrator(double stepSize, DifferentialEquationInterface equation, int cachePlaces, NumericalIntegratorType primerIntegrationMethod, int startingSubSteps)	constructs a new CachingNumericalIntegrator with a fixed number of cache places.

Method Summary

Modifier and Type	Method	Description
double[]	getDY(int numberDown)	get a cached dY-value.
double[]	getY(int numberDown)	get a cached Y-value.
abstract double[]	next(double x)	The integrators that extend the CachingNumericalIntegrator calculate the value of y(x+stepSize) just based on the x-value.
double[]	next(double x, double[] y)	computes the next value.
void	setStepSize(double stepSize)

Methods inherited from class nl.tudelft.simulation.jstats.ode.integrators.NumericalIntegrator

add, add, add, add, add, getError, getStepSize, multiply

Methods inherited from class java.lang.Object

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

Field Details

startingIntegrator

protected NumericalIntegrator startingIntegrator

The primer integrator.

startingSubSteps

protected int startingSubSteps

the substeps to use when starting the integrator.

Constructor Details

CachingNumericalIntegrator

public CachingNumericalIntegrator(double stepSize,
 DifferentialEquationInterface equation,
 int cachePlaces,
 NumericalIntegratorType primerIntegrationMethod,
 int startingSubSteps)

constructs a new CachingNumericalIntegrator with a fixed number of cache places.

Parameters:

stepSize - double; the stepSize

equation - DifferentialEquationInterface; the differentialEquation

cachePlaces - int; the number of cache places to store

primerIntegrationMethod - NumericalIntegratorType; the primer integrator to use

startingSubSteps - int; the number of sub-steps per stepSize during starting of the integrator

Method Details

setStepSize

public void setStepSize(double stepSize)

Overrides:

setStepSize in class NumericalIntegrator

Parameters:

stepSize - double; The step size to set.

next

public double[] next(double x,
 double[] y)

computes the next value.

Specified by:

next in class NumericalIntegrator

Parameters:

x - double; the x value corresponding to the last y-value computed

y - double[]; the last y value

Returns:

the new value

getY

public double[] getY(int numberDown)

get a cached Y-value.

Parameters:

numberDown - int; the number of the previous value we want

Returns:

the corresponding Y-value

getDY

public double[] getDY(int numberDown)

get a cached dY-value.

Parameters:

numberDown - int; the number of the previous value we want

Returns:

the corresponding dY-value

next

public abstract double[] next(double x)

The integrators that extend the CachingNumericalIntegrator calculate the value of y(x+stepSize) just based on the x-value. They retrieve y(x), y(x-stepSize), etc. or y(k), y(k-1) all from the cache.

Parameters:

x - double; the x-value to use in the calculation

Returns:

the value of y(x+stepSize)