Package org.hipparchus.ode

Class AbstractIntegrator

java.lang.Object

org.hipparchus.ode.AbstractIntegrator

All Implemented Interfaces:

ODEIntegrator

Direct Known Subclasses:

AdaptiveStepsizeIntegrator, FixedStepRungeKuttaIntegrator

public abstract class AbstractIntegrator
extends Object
implements ODEIntegrator

Base class managing common boilerplate for all integrators.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractIntegrator(String name)	Build an instance.

Method Summary

Modifier and Type	Method	Description
protected ODEStateAndDerivative	acceptStep(AbstractODEStateInterpolator interpolator, double tEnd)	Accept a step, triggering events and step handlers.
void	addEventDetector(ODEEventDetector detector)	Add an event detector to the integrator.
void	addStepEndHandler(ODEStepEndHandler handler)	Add a handler for step ends to the integrator.
void	addStepHandler(ODEStepHandler handler)	Add a step handler to this integrator.
void	clearEventDetectors()	Remove all the event handlers that have been added to the integrator.
void	clearStepEndHandlers()	Remove all the handlers for step ends that have been added to the integrator.
void	clearStepHandlers()	Remove all the step handlers that have been added to the integrator.
double[]	computeDerivatives(double t, double[] y)	Compute the derivatives and check the number of evaluations.
double	getCurrentSignedStepsize()	Get the current signed value of the integration stepsize.
protected ExpandableODE	getEquations()	Get the differential equations to integrate.
int	getEvaluations()	Get the number of evaluations of the differential equations function.
protected Incrementor	getEvaluationsCounter()	Get the evaluations counter.
List<ODEEventDetector>	getEventDetectors()	Get all the event detectors that have been added to the integrator.
int	getMaxEvaluations()	Get the maximal number of functions evaluations.
String	getName()	Get the name of the method.
List<ODEStepEndHandler>	getStepEndHandlers()	Get all the handlers for step ends that have been added to the integrator.
List<ODEStepHandler>	getStepHandlers()	Get all the step handlers that have been added to the integrator.
protected double	getStepSize()	Get the current step size.
ODEStateAndDerivative	getStepStart()	Get the state at step start time ti.
protected void	incrementEvaluations(int nTimes)	Increment evaluations of derivatives.
protected ODEStateAndDerivative	initIntegration(ExpandableODE eqn, ODEState s0, double 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(ODEState initialState, double 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(double stepSize)	Set the current step size.
protected void	setStepStart(ODEStateAndDerivative 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.hipparchus.ode.ODEIntegrator

integrate, integrate

Constructor Details

AbstractIntegrator

protected AbstractIntegrator(String name)

Build an instance.

Parameters:

name - name of the method

Method Details

getName

public String getName()

Get the name of the method.

Specified by:

getName in interface ODEIntegrator

Returns:

name of the method

addStepHandler

public void addStepHandler(ODEStepHandler 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 ODEIntegrator

Parameters:

handler - handler for the accepted steps

See Also:

• ODEIntegrator.getStepHandlers()
• ODEIntegrator.clearStepHandlers()

getStepHandlers

public List<ODEStepHandler> getStepHandlers()

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

Specified by:

getStepHandlers in interface ODEIntegrator

Returns:

an unmodifiable collection of the added events handlers

See Also:

• ODEIntegrator.addStepHandler(ODEStepHandler)
• ODEIntegrator.clearStepHandlers()

clearStepHandlers

public void clearStepHandlers()

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

Specified by:

clearStepHandlers in interface ODEIntegrator

See Also:

• ODEIntegrator.addStepHandler(ODEStepHandler)
• ODEIntegrator.getStepHandlers()

addEventDetector

public void addEventDetector(ODEEventDetector detector)

Add an event detector to the integrator.

Specified by:

addEventDetector in interface ODEIntegrator

Parameters:

detector - event detector

See Also:

• ODEIntegrator.getEventDetectors()
• ODEIntegrator.clearEventDetectors()

getEventDetectors

public List<ODEEventDetector> getEventDetectors()

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

Specified by:

getEventDetectors in interface ODEIntegrator

Returns:

an unmodifiable list of the added events detectors

See Also:

• ODEIntegrator.addEventDetector(ODEEventDetector)
• ODEIntegrator.clearEventDetectors()

clearEventDetectors

public void clearEventDetectors()

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

Specified by:

clearEventDetectors in interface ODEIntegrator

See Also:

• ODEIntegrator.addEventDetector(ODEEventDetector)
• ODEIntegrator.getEventDetectors()

addStepEndHandler

public void addStepEndHandler(ODEStepEndHandler handler)

Add a handler for step ends to the integrator.

The stepEndOccurred(state, forward) method of the handler will be called at each step end.

Specified by:

addStepEndHandler in interface ODEIntegrator

Parameters:

handler - handler for step ends

See Also:

• ODEIntegrator.getStepEndHandlers()
• ODEIntegrator.clearStepEndHandlers()

getStepEndHandlers

public List<ODEStepEndHandler> getStepEndHandlers()

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

Specified by:

getStepEndHandlers in interface ODEIntegrator

Returns:

an unmodifiable list of the added step end handlers

See Also:

• ODEIntegrator.addStepEndHandler(ODEStepEndHandler)
• ODEIntegrator.clearStepEndHandlers()

clearStepEndHandlers

public void clearStepEndHandlers()

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

Specified by:

clearStepEndHandlers in interface ODEIntegrator

See Also:

• ODEIntegrator.addStepEndHandler(ODEStepEndHandler)
• ODEIntegrator.getStepEndHandlers()

getCurrentSignedStepsize

public double 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 ODEIntegrator

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 ODEIntegrator

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 ODEIntegrator

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 ODEIntegrator

Returns:

number of evaluations of the differential equations function

initIntegration

protected ODEStateAndDerivative initIntegration(ExpandableODE eqn,
 ODEState s0,
 double t)

Prepare the start of an integration.

Parameters:

eqn - equations to integrate

s0 - initial state vector

t - target time for the integration

Returns:

Initial state with computed derivatives.

getEquations

protected ExpandableODE getEquations()

Get the differential equations to integrate.

Returns:

differential equations to integrate

getEvaluationsCounter

protected Incrementor getEvaluationsCounter()

Get the evaluations counter.

Returns:

evaluations counter

computeDerivatives

public double[] computeDerivatives(double t,
 double[] y)
                            throws MathIllegalArgumentException,
MathIllegalStateException,
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:

MathIllegalArgumentException - if arrays dimensions do not match equations settings

MathIllegalStateException - 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

incrementEvaluations

protected void incrementEvaluations(int nTimes)

Increment evaluations of derivatives.

Parameters:

nTimes - number of evaluations to increment

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 ODEStateAndDerivative acceptStep(AbstractODEStateInterpolator interpolator,
 double tEnd)
                                    throws MathIllegalArgumentException,
MathIllegalStateException

Accept a step, triggering events and step handlers.

Parameters:

interpolator - step interpolator

tEnd - final integration time

Returns:

state at end of step

Throws:

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

MathIllegalArgumentException - if the location of an event cannot be bracketed

MathIllegalArgumentException - if arrays dimensions do not match equations settings

sanityChecks

protected void sanityChecks(ODEState initialState,
 double t)
                     throws MathIllegalArgumentException

Check the integration span.

Parameters:

initialState - initial state

t - target time for the integration

Throws:

MathIllegalArgumentException - if integration span is too small

MathIllegalArgumentException - 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(double stepSize)

Set the current step size.

Parameters:

stepSize - step size to set

getStepSize

protected double getStepSize()

Get the current step size.

Returns:

current step size

setStepStart

protected void setStepStart(ODEStateAndDerivative stepStart)

Set current step start.

Parameters:

stepStart - step start

getStepStart

public ODEStateAndDerivative getStepStart()

Get the state at 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:

getStepStart in interface ODEIntegrator

Returns:

state at step start time t_i

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