Package org.orekit.propagation.events

Class EventState<T extends EventDetector>

java.lang.Object

org.orekit.propagation.events.EventState<T>

Type Parameters:

T - class type for the generic version

All Implemented Interfaces:

Serializable

public class EventState<T extends EventDetector>
extends Object
implements Serializable

This class handles the state for one event detector during integration steps.

This class is heavily based on the class with the same name from the Hipparchus library. The changes performed consist in replacing raw types (double and double arrays) with space dynamics types (AbsoluteDate, SpacecraftState).

Each time the propagator proposes a step, the event detector should be checked. This class handles the state of one detector during one propagation step, with references to the state at the end of the preceding step. This information is used to determine if the detector should trigger an event or not during the proposed step (and hence the step should be reduced to ensure the event occurs at a bound rather than inside the step).

Author:

Luc Maisonobe

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	EventState.EventOccurrence	Class to hold the data related to an event occurrence that is needed to decide how to modify integration.

Constructor Summary

Constructors

Constructor	Description
EventState(T detector)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
EventState.EventOccurrence	doEvent(SpacecraftState state)	Notify the user's listener of the event.
boolean	evaluateStep(OrekitStepInterpolator interpolator)	Evaluate the impact of the proposed step on the event detector.
AbsoluteDate	getEventDate()	Get the occurrence time of the event triggered in the current step.
T	getEventDetector()	Get the underlying event detector.
void	init(SpacecraftState s0, AbsoluteDate t)	Initialize event handler at the start of a propagation.
void	reinitializeBegin(OrekitStepInterpolator interpolator)	Reinitialize the beginning of the step.
boolean	tryAdvance(SpacecraftState state, OrekitStepInterpolator interpolator)	Try to accept the current history up to the given time.

Methods inherited from class java.lang.Object

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

Constructor Detail

EventState

public EventState(T detector)

Simple constructor.

Parameters:

detector - monitored event detector

Method Detail

getEventDetector

public T getEventDetector()

Get the underlying event detector.

Returns:

underlying event detector

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)
          throws OrekitException

Initialize event handler at the start of a propagation.

This method is called once at the start of the propagation. It may be used by the event handler to initialize some internal data if needed.

Parameters:

s0 - initial state

t - target time for the integration

Throws:

OrekitException - if some specific error occurs

reinitializeBegin

public void reinitializeBegin(OrekitStepInterpolator interpolator)
                       throws OrekitException

Reinitialize the beginning of the step.

Parameters:

interpolator - interpolator valid for the current step

Throws:

OrekitException - if the event detector value cannot be evaluated at the beginning of the step

evaluateStep

public boolean evaluateStep(OrekitStepInterpolator interpolator)
                     throws OrekitException,
                            MathRuntimeException

Evaluate the impact of the proposed step on the event detector.

Parameters:

interpolator - step interpolator for the proposed step

Returns:

true if the event detector triggers an event before the end of the proposed step (this implies the step should be rejected)

Throws:

OrekitException - if the switching function cannot be evaluated

MathRuntimeException - if an event cannot be located

getEventDate

public AbsoluteDate getEventDate()

Get the occurrence time of the event triggered in the current step.

Returns:

occurrence time of the event triggered in the current step.

tryAdvance

public boolean tryAdvance(SpacecraftState state,
                          OrekitStepInterpolator interpolator)
                   throws OrekitException

Try to accept the current history up to the given time.

It is not necessary to call this method before calling doEvent(SpacecraftState) with the same state. It is necessary to call this method before you call doEvent(SpacecraftState) on some other event detector.

Parameters:

state - to try to accept.

interpolator - to use to find the new root, if any.

Returns:

if the event detector has an event it has not detected before that is on or before the same time as state. In other words false means continue on while true means stop and handle my event first.

Throws:

OrekitException - if the g function throws one

doEvent

public EventState.EventOccurrence doEvent(SpacecraftState state)
                                   throws OrekitException

Notify the user's listener of the event. The event occurs wholly within this method call including a call to EventDetector.resetState(SpacecraftState) if necessary.

Parameters:

state - the state at the time of the event. This must be at the same time as the current value of getEventDate().

Returns:

the user's requested action and the new state if the action is Action.RESET_STATE. Otherwise the new state is state. The stop time indicates what time propagation should stop if the action is Action.STOP. This guarantees the integration will stop on or after the root, so that integration may be restarted safely.

Throws:

OrekitException - if the event detector throws one