Package org.apache.commons.math4.legacy.ode

Class AbstractFieldIntegrator<T extends RealFieldElement<T>>

java.lang.Object

org.apache.commons.math4.legacy.ode.AbstractFieldIntegrator<T>

Type Parameters:

T - the type of the field elements

All Implemented Interfaces:

FirstOrderFieldIntegrator<T>

Direct Known Subclasses:

AdaptiveStepsizeFieldIntegrator, RungeKuttaFieldIntegrator

public abstract class AbstractFieldIntegrator<T extends RealFieldElement<T>>
extends Object
implements FirstOrderFieldIntegrator<T>

Base class managing common boilerplate for all integrators.

Since:

3.6

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractFieldIntegrator(Field<T> field, String name)	Build an instance.

Method Summary

Modifier and Type	Method	Description
protected FieldODEStateAndDerivative<T>	acceptStep(AbstractFieldStepInterpolator<T> interpolator, T tEnd)	Accept a step, triggering events and step handlers.
void	addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, double convergence, int maxIterationCount)	Add an event handler to the integrator.
void	addEventHandler(FieldEventHandler<T> handler, double maxCheckInterval, double convergence, int maxIterationCount, BracketedRealFieldUnivariateSolver<T> solver)	Add an event handler to the integrator.
void	addStepHandler(FieldStepHandler<T> handler)	Add a step handler to this integrator.
void	clearEventHandlers()	Remove all the event handlers that have been added to the integrator.
void	clearStepHandlers()	Remove all the step handlers that have been added to the integrator.
T[]	computeDerivatives(T t, T[] y)	Compute the derivatives and check the number of evaluations.
T	getCurrentSignedStepsize()	Get the current signed value of the integration stepsize.
FieldODEStateAndDerivative<T>	getCurrentStepStart()	Get the current value of the step start time ti.
protected FieldExpandableODE<T>	getEquations()	Get the differential equations to integrate.
int	getEvaluations()	Get the number of evaluations of the differential equations function.
protected IntegerSequence.Incrementor	getEvaluationsCounter()	Get the evaluations counter.
Collection<FieldEventHandler<T>>	getEventHandlers()	Get all the event handlers that have been added to the integrator.
Field<T>	getField()	Get the field to which state vector elements belong.
int	getMaxEvaluations()	Get the maximal number of functions evaluations.
String	getName()	Get the name of the method.
Collection<FieldStepHandler<T>>	getStepHandlers()	Get all the step handlers that have been added to the integrator.
protected T	getStepSize()	Get the current step size.
protected FieldODEStateAndDerivative<T>	getStepStart()	Getcurrent step start.
protected FieldODEStateAndDerivative<T>	initIntegration(FieldExpandableODE<T> eqn, T t0, T[] y0, T t)	Prepare the start of an integration.
protected boolean	isLastStep()	Check if this step is the last one.
protected boolean	resetOccurred()	Check if a reset occurred while last step was accepted.
protected void	sanityChecks(FieldODEState<T> eqn, T t)	Check the integration span.
protected void	setIsLastStep(boolean isLastStep)	Set the last state flag.
void	setMaxEvaluations(int maxEvaluations)	Set the maximal number of differential equations function evaluations.
protected void	setStateInitialized(boolean stateInitialized)	Set the stateInitialized flag.
protected void	setStepSize(T stepSize)	Set the current step size.
protected void	setStepStart(FieldODEStateAndDerivative<T> stepStart)	Set current step start.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.math4.legacy.ode.FirstOrderFieldIntegrator

integrate

Constructor Detail

AbstractFieldIntegrator

protected AbstractFieldIntegrator(Field<T> field,
                                  String name)

Build an instance.

Parameters:

field - field to which the time and state vector elements belong

name - name of the method

Method Detail

getField

public Field<T> getField()

Get the field to which state vector elements belong.

Returns:

field to which state vector elements belong

getName

public String getName()

Get the name of the method.

Specified by:

getName in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

name of the method

addStepHandler

public void addStepHandler(FieldStepHandler<T> handler)

Add a step handler to this integrator.

The handler will be called by the integrator for each accepted step.

Specified by:

addStepHandler in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Parameters:

handler - handler for the accepted steps

See Also:

FirstOrderFieldIntegrator.getStepHandlers(), FirstOrderFieldIntegrator.clearStepHandlers()

getStepHandlers

public Collection<FieldStepHandler<T>> getStepHandlers()

Get all the step handlers that have been added to the integrator.

Specified by:

getStepHandlers in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

an unmodifiable collection of the added events handlers

See Also:

FirstOrderFieldIntegrator.addStepHandler(FieldStepHandler), FirstOrderFieldIntegrator.clearStepHandlers()

clearStepHandlers

public void clearStepHandlers()

Remove all the step handlers that have been added to the integrator.

Specified by:

clearStepHandlers in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

See Also:

FirstOrderFieldIntegrator.addStepHandler(FieldStepHandler), FirstOrderFieldIntegrator.getStepHandlers()

addEventHandler

public void addEventHandler(FieldEventHandler<T> handler,
                            double maxCheckInterval,
                            double convergence,
                            int maxIterationCount)

Add an event handler to the integrator.

The default solver is a 5^th order FieldBracketingNthOrderBrentSolver.

Specified by:

addEventHandler in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Parameters:

handler - event handler

maxCheckInterval - maximal time interval between switching function checks (this interval prevents missing sign changes in case the integration steps becomes very large)

convergence - convergence threshold in the event time search

maxIterationCount - upper limit of the iteration count in the event time search events.

See Also:

FirstOrderFieldIntegrator.addEventHandler(FieldEventHandler, double, double, int, org.apache.commons.math4.legacy.analysis.solvers.BracketedRealFieldUnivariateSolver), FirstOrderFieldIntegrator.getEventHandlers(), FirstOrderFieldIntegrator.clearEventHandlers()

addEventHandler

public void addEventHandler(FieldEventHandler<T> handler,
                            double maxCheckInterval,
                            double convergence,
                            int maxIterationCount,
                            BracketedRealFieldUnivariateSolver<T> solver)

Add an event handler to the integrator.

Specified by:

addEventHandler in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Parameters:

handler - event handler

maxCheckInterval - maximal time interval between switching function checks (this interval prevents missing sign changes in case the integration steps becomes very large)

convergence - convergence threshold in the event time search

maxIterationCount - upper limit of the iteration count in the event time search events.

solver - solver to use to locate the event

See Also:

FirstOrderFieldIntegrator.addEventHandler(FieldEventHandler, double, double, int), FirstOrderFieldIntegrator.getEventHandlers(), FirstOrderFieldIntegrator.clearEventHandlers()

getEventHandlers

public Collection<FieldEventHandler<T>> getEventHandlers()

Get all the event handlers that have been added to the integrator.

Specified by:

getEventHandlers in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

an unmodifiable collection of the added events handlers

See Also:

FirstOrderFieldIntegrator.addEventHandler(FieldEventHandler, double, double, int), FirstOrderFieldIntegrator.clearEventHandlers()

clearEventHandlers

public void clearEventHandlers()

Remove all the event handlers that have been added to the integrator.

Specified by:

clearEventHandlers in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

See Also:

FirstOrderFieldIntegrator.addEventHandler(FieldEventHandler, double, double, int), FirstOrderFieldIntegrator.getEventHandlers()

getCurrentStepStart

public FieldODEStateAndDerivative<T> getCurrentStepStart()

Get the current value of the step start time t_i.

This method can be called during integration (typically by the object implementing the differential equations problem) if the value of the current step that is attempted is needed.

The result is undefined if the method is called outside of calls to integrate.

Specified by:

getCurrentStepStart in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

current value of the state at step start time t_i

getCurrentSignedStepsize

public T getCurrentSignedStepsize()

Get the current signed value of the integration stepsize.

This method can be called during integration (typically by the object implementing the differential equations problem) if the signed value of the current stepsize that is tried is needed.

The result is undefined if the method is called outside of calls to integrate.

Specified by:

getCurrentSignedStepsize in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

current signed value of the stepsize

setMaxEvaluations

public void setMaxEvaluations(int maxEvaluations)

Set the maximal number of differential equations function evaluations.

The purpose of this method is to avoid infinite loops which can occur for example when stringent error constraints are set or when lots of discrete events are triggered, thus leading to many rejected steps.

Specified by:

setMaxEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Parameters:

maxEvaluations - maximal number of function evaluations (negative values are silently converted to maximal integer value, thus representing almost unlimited evaluations)

getMaxEvaluations

public int getMaxEvaluations()

Get the maximal number of functions evaluations.

Specified by:

getMaxEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

maximal number of functions evaluations

getEvaluations

public int getEvaluations()

Get the number of evaluations of the differential equations function.

The number of evaluations corresponds to the last call to the integrate method. It is 0 if the method has not been called yet.

Specified by:

getEvaluations in interface FirstOrderFieldIntegrator<T extends RealFieldElement<T>>

Returns:

number of evaluations of the differential equations function

initIntegration

protected FieldODEStateAndDerivative<T> initIntegration(FieldExpandableODE<T> eqn,
                                                        T t0,
                                                        T[] y0,
                                                        T t)

Prepare the start of an integration.

Parameters:

eqn - equations to integrate

t0 - start value of the independent time variable

y0 - array containing the start value of the state vector

t - target time for the integration

Returns:

initial state with derivatives added

getEquations

protected FieldExpandableODE<T> getEquations()

Get the differential equations to integrate.

Returns:

differential equations to integrate

getEvaluationsCounter

protected IntegerSequence.Incrementor getEvaluationsCounter()

Get the evaluations counter.

Returns:

evaluations counter

computeDerivatives

public T[] computeDerivatives(T t,
                              T[] y)
                       throws DimensionMismatchException,
                              MaxCountExceededException,
                              NullPointerException

Compute the derivatives and check the number of evaluations.

Parameters:

t - current value of the independent time variable

y - array containing the current value of the state vector

Returns:

state completed with derivatives

Throws:

DimensionMismatchException - if arrays dimensions do not match equations settings

MaxCountExceededException - if the number of functions evaluations is exceeded

NullPointerException - if the ODE equations have not been set (i.e. if this method is called outside of a call to integrate

setStateInitialized

protected void setStateInitialized(boolean stateInitialized)

Set the stateInitialized flag.

This method must be called by integrators with the value false before they start integration, so a proper lazy initialization is done automatically on the first step.

Parameters:

stateInitialized - new value for the flag

acceptStep

protected FieldODEStateAndDerivative<T> acceptStep(AbstractFieldStepInterpolator<T> interpolator,
                                                   T tEnd)
                                            throws MaxCountExceededException,
                                                   DimensionMismatchException,
                                                   NoBracketingException

Accept a step, triggering events and step handlers.

Parameters:

interpolator - step interpolator

tEnd - final integration time

Returns:

state at end of step

Throws:

MaxCountExceededException - if the interpolator throws one because the number of functions evaluations is exceeded

NoBracketingException - if the location of an event cannot be bracketed

DimensionMismatchException - if arrays dimensions do not match equations settings

sanityChecks

protected void sanityChecks(FieldODEState<T> eqn,
                            T t)
                     throws NumberIsTooSmallException,
                            DimensionMismatchException

Check the integration span.

Parameters:

eqn - set of differential equations

t - target time for the integration

Throws:

NumberIsTooSmallException - if integration span is too small

DimensionMismatchException - if adaptive step size integrators tolerance arrays dimensions are not compatible with equations settings

resetOccurred

protected boolean resetOccurred()

Check if a reset occurred while last step was accepted.

Returns:

true if a reset occurred while last step was accepted

setStepSize

protected void setStepSize(T stepSize)

Set the current step size.

Parameters:

stepSize - step size to set

getStepSize

protected T getStepSize()

Get the current step size.

Returns:

current step size

setStepStart

protected void setStepStart(FieldODEStateAndDerivative<T> stepStart)

Set current step start.

Parameters:

stepStart - step start

getStepStart

protected FieldODEStateAndDerivative<T> getStepStart()

Getcurrent step start.

Returns:

current step start

setIsLastStep

protected void setIsLastStep(boolean isLastStep)

Set the last state flag.

Parameters:

isLastStep - if true, this step is the last one

isLastStep

protected boolean isLastStep()

Check if this step is the last one.

Returns:

true if this step is the last one