agi.foundation.numericalmethods.advanced

(agi.foundation.core-2025r1.jar)

Class RungeKuttaFixedStepIntegrator

java.lang.Object

agi.foundation.numericalmethods.NumericalIntegrator

agi.foundation.numericalmethods.advanced.RungeKuttaFixedStepIntegrator

All Implemented Interfaces:

ICloneWithContext, IThreadAware

Direct Known Subclasses:

RungeKutta4Integrator

public abstract class RungeKuttaFixedStepIntegrator
extends NumericalIntegrator

Defines a Runge-Kutta integrator with a fixed step size.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RungeKuttaFixedStepIntegrator(RungeKuttaAlgorithm tableau) Initializes a new instance based on the given tableau.
protected	RungeKuttaFixedStepIntegrator(RungeKuttaAlgorithm tableau, DependentVariableDerivatives system) Initializes a new instance based on the given tableau and on the given differential system for the derivatives of the dependent variables.
protected	RungeKuttaFixedStepIntegrator(RungeKuttaFixedStepIntegrator existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
double	getCurrentStepSize() Gets the current (positive) size of the step which the integrator will use for the next integration step.
protected RungeKuttaAlgorithm	getTableau() Gets the Butcher Tableau with the coefficients and weights to use to perform the RungeKutta integration.
void	initialize(double x, double[] y) Initialize the integrator's initial independent and dependent variables and reset the integration parameters.
void	reintegrate(double stepSize) Repeats the last integration of the differential equations.
protected void	setTableau(RungeKuttaAlgorithm value) Sets the Butcher Tableau with the coefficients and weights to use to perform the RungeKutta integration.

Methods inherited from class agi.foundation.numericalmethods.NumericalIntegrator

clone, getDimension, getDirection, getFinalDependentVariableValues, getFinalIndependentVariableValue, getInitialDependentVariableValues, getInitialIndependentVariableValue, getInitialStepSize, getIsThreadSafe, getPreviousStepSize, getStepSizeInformation, getSystemOfEquations, integrate, integrate, setDirection, setFinalDependentVariableValues, setFinalIndependentVariableValue, setInitialDependentVariableValues, setInitialIndependentVariableValue, setInitialStepSize, setStepSizeInformation, setSystemOfEquations, startNextStep

Methods inherited from class java.lang.Object

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

Constructor Detail

RungeKuttaFixedStepIntegrator

protected RungeKuttaFixedStepIntegrator(RungeKuttaAlgorithm tableau)

Initializes a new instance based on the given tableau.

Parameters:

tableau - The Butcher Tableau containing the coefficients and weights for the algorithm.

RungeKuttaFixedStepIntegrator

protected RungeKuttaFixedStepIntegrator(RungeKuttaAlgorithm tableau,
                                        DependentVariableDerivatives system)

Initializes a new instance based on the given tableau and on the given differential system for the derivatives of the dependent variables.

Parameters:

tableau - The Butcher Tableau containing the coefficients and weights for the algorithm.

system - The system of differential equations defining the derivatives for the dependent variables.

RungeKuttaFixedStepIntegrator

protected RungeKuttaFixedStepIntegrator(@Nonnull
                                        RungeKuttaFixedStepIntegrator existingInstance,
                                        @Nonnull
                                        CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

getTableau

protected final RungeKuttaAlgorithm getTableau()

Gets the Butcher Tableau with the coefficients and weights to use to perform the RungeKutta integration.

setTableau

protected final void setTableau(RungeKuttaAlgorithm value)

Sets the Butcher Tableau with the coefficients and weights to use to perform the RungeKutta integration.

getCurrentStepSize

public double getCurrentStepSize()

Gets the current (positive) size of the step which the integrator will use for the next integration step.

Specified by:

getCurrentStepSize in class NumericalIntegrator

initialize

public void initialize(double x,
                       double[] y)

Initialize the integrator's initial independent and dependent variables and reset the integration parameters. This should be called by the user prior to performing the first integration step.

Overrides:

initialize in class NumericalIntegrator

Parameters:

x - The value of the initial independent variable.

y - The values for the initial dependent variables.

reintegrate

public void reintegrate(double stepSize)

Repeats the last integration of the differential equations.

When overriding this method, note that the CurrentStepSize (get) property should be unaffected by the stepSize parameter.

Specified by:

reintegrate in class NumericalIntegrator

Parameters:

stepSize - The increment made to the InitialIndependentVariableValue (get / set) to transition to the new FinalIndependentVariableValue (get / set).