org.hipparchus.ode

Interface ODEIntegrator

All Known Implementing Classes:

AbstractIntegrator, AdamsBashforthIntegrator, AdamsIntegrator, AdamsMoultonIntegrator, AdaptiveStepsizeIntegrator, ClassicalRungeKuttaIntegrator, DormandPrince54Integrator, DormandPrince853Integrator, EmbeddedRungeKuttaIntegrator, EulerIntegrator, GillIntegrator, GraggBulirschStoerIntegrator, HighamHall54Integrator, LutherIntegrator, MidpointIntegrator, MultistepIntegrator, RungeKuttaIntegrator, ThreeEighthesIntegrator

public interface ODEIntegrator

This interface represents a first order integrator for differential equations.

The classes which are devoted to solve first order differential equations should implement this interface. The problems which can be handled should implement the OrdinaryDifferentialEquation interface.

See Also:

OrdinaryDifferentialEquation, ODEStepHandler, ODEEventHandler

Method Summary

Modifier and Type	Method and Description
void	addEventHandler(ODEEventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount) Add an event handler to the integrator.
void	addEventHandler(ODEEventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount, BracketedUnivariateSolver<UnivariateFunction> solver) Add an event handler to the integrator.
void	addStepHandler(ODEStepHandler 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.
double	getCurrentSignedStepsize() Get the current signed value of the integration stepsize.
double	getCurrentStepStart() Deprecated. as of 1.0, replaced with getStepStart().getTime()
int	getEvaluations() Get the number of evaluations of the differential equations function.
Collection<ODEEventHandler>	getEventHandlers() Get all the event handlers that have been added to the integrator.
int	getMaxEvaluations() Get the maximal number of functions evaluations.
String	getName() Get the name of the method.
Collection<ODEStepHandler>	getStepHandlers() Get all the step handlers that have been added to the integrator.
ODEStateAndDerivative	getStepStart() Get the state at step start time ti.
ODEStateAndDerivative	integrate(ExpandableODE equations, ODEState initialState, double finalTime) Integrate the differential equations up to the given time.
default double	integrate(OrdinaryDifferentialEquation equations, double t0, double[] y0, double t, double[] y) Deprecated. as of 1.0, replaced with integrate(ExpandableODE, ODEState, double)
default ODEStateAndDerivative	integrate(OrdinaryDifferentialEquation equations, ODEState initialState, double finalTime) Integrate the differential equations up to the given time.
void	setMaxEvaluations(int maxEvaluations) Set the maximal number of differential equations function evaluations.

Method Detail

getName

String getName()

Get the name of the method.

Returns:

name of the method

addStepHandler

void addStepHandler(ODEStepHandler handler)

Add a step handler to this integrator.

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

Parameters:

handler - handler for the accepted steps

See Also:

getStepHandlers(), clearStepHandlers()

getStepHandlers

Collection<ODEStepHandler> getStepHandlers()

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

Returns:

an unmodifiable collection of the added events handlers

See Also:

addStepHandler(ODEStepHandler), clearStepHandlers()

clearStepHandlers

void clearStepHandlers()

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

See Also:

addStepHandler(ODEStepHandler), getStepHandlers()

addEventHandler

void addEventHandler(ODEEventHandler handler,
                     double maxCheckInterval,
                     double convergence,
                     int maxIterationCount)

Add an event handler to the integrator.

Uses a default UnivariateSolver with an absolute accuracy equal to the given convergence threshold, as root-finding algorithm to detect the state events.

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. Must be smaller than maxCheckInterval and should be small compared to time scale of the ODE dynamics.

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

See Also:

getEventHandlers(), clearEventHandlers()

addEventHandler

void addEventHandler(ODEEventHandler handler,
                     double maxCheckInterval,
                     double convergence,
                     int maxIterationCount,
                     BracketedUnivariateSolver<UnivariateFunction> solver)

Add an event handler to the integrator.

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. Must be smaller than maxCheckInterval and should be small compared to time scale of the ODE dynamics.

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

solver - The root-finding algorithm to use to detect the state events.

See Also:

getEventHandlers(), clearEventHandlers()

getEventHandlers

Collection<ODEEventHandler> getEventHandlers()

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

Returns:

an unmodifiable collection of the added events handlers

See Also:

addEventHandler(ODEEventHandler, double, double, int), clearEventHandlers()

clearEventHandlers

void clearEventHandlers()

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

See Also:

addEventHandler(ODEEventHandler, double, double, int), getEventHandlers()

getCurrentStepStart

@Deprecated
double getCurrentStepStart()

Deprecated. as of 1.0, replaced with getStepStart().getTime()

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.

Returns:

current value of the step start time t_i

getStepStart

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.

Returns:

state at step start time t_i

getCurrentSignedStepsize

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.

Returns:

current signed value of the stepsize

setMaxEvaluations

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.

Parameters:

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

getMaxEvaluations

int getMaxEvaluations()

Get the maximal number of functions evaluations.

Returns:

maximal number of functions evaluations

getEvaluations

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.

Returns:

number of evaluations of the differential equations function

integrate

ODEStateAndDerivative integrate(ExpandableODE equations,
                                ODEState initialState,
                                double finalTime)
                         throws MathIllegalArgumentException,
                                MathIllegalStateException

Integrate the differential equations up to the given time.

This method solves an Initial Value Problem (IVP).

Since this method stores some internal state variables made available in its public interface during integration (getCurrentSignedStepsize()), it is not thread-safe.

Parameters:

equations - differential equations to integrate

initialState - initial state (time, primary and secondary state vectors)

finalTime - target time for the integration (can be set to a value smaller than t0 for backward integration)

Returns:

final state, its time will be the same as finalTime if integration reached its target, but may be different if some ODEEventHandler stops it at some point.

Throws:

MathIllegalArgumentException - if integration step is too small

MathIllegalStateException - if the number of functions evaluations is exceeded

MathIllegalArgumentException - if the location of an event cannot be bracketed

integrate

default ODEStateAndDerivative integrate(OrdinaryDifferentialEquation equations,
                                        ODEState initialState,
                                        double finalTime)
                                 throws MathIllegalArgumentException,
                                        MathIllegalStateException

Integrate the differential equations up to the given time.

This method solves an Initial Value Problem (IVP).

Since this method stores some internal state variables made available in its public interface during integration (getCurrentSignedStepsize()), it is not thread-safe.

Parameters:

equations - differential equations to integrate

initialState - initial state (time, primary and secondary state vectors)

finalTime - target time for the integration (can be set to a value smaller than t0 for backward integration)

Returns:

final state, its time will be the same as finalTime if integration reached its target, but may be different if some ODEEventHandler stops it at some point.

Throws:

MathIllegalArgumentException - if integration step is too small

MathIllegalStateException - if the number of functions evaluations is exceeded

MathIllegalArgumentException - if the location of an event cannot be bracketed

integrate

@Deprecated
default double integrate(OrdinaryDifferentialEquation equations,
                                     double t0,
                                     double[] y0,
                                     double t,
                                     double[] y)
                              throws MathIllegalArgumentException,
                                     MathIllegalStateException

Deprecated. as of 1.0, replaced with integrate(ExpandableODE, ODEState, double)

Integrate the differential equations up to the given time.

This method solves an Initial Value Problem (IVP).

Since this method stores some internal state variables made available in its public interface during integration (getCurrentSignedStepsize()), it is not thread-safe.

Parameters:

equations - differential equations to integrate

t0 - initial time

y0 - initial value of the state vector at t0

t - target time for the integration (can be set to a value smaller than t0 for backward integration)

y - placeholder where to put the state vector at each successful step (and hence at the end of integration), can be the same object as y0

Returns:

stop time, will be the same as target time if integration reached its target, but may be different if some ODEEventHandler stops it at some point.

Throws:

MathIllegalArgumentException - if arrays dimension do not match equations settings

MathIllegalArgumentException - if integration step is too small

MathIllegalStateException - if the number of functions evaluations is exceeded

MathIllegalArgumentException - if the location of an event cannot be bracketed