Package org.orekit.propagation.events

Class FieldEventEnablingPredicateFilter<T extends CalculusFieldElement<T>>

java.lang.Object

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

Type Parameters:

T - type of the field elements

All Implemented Interfaces:

FieldDetectorModifier<T>, FieldEventDetector<T>

public class FieldEventEnablingPredicateFilter<T extends CalculusFieldElement<T>>
extends Object
implements FieldDetectorModifier<T>

Wrapper used to detect events only when enabled by an external predicated function.

General events are defined implicitly by a g function crossing zero. This implies that during an orbit propagation, events are triggered at all zero crossings.

Sometimes, users would like to enable or disable events by themselves, for example to trigger them only for certain orbits, or to check elevation maximums only when elevation itself is positive (i.e. they want to discard elevation maximums below ground). In these cases, looking precisely for all events location and triggering events that will later be ignored is a waste of computing time.

Users can wrap a regular event detector in an instance of this class and provide this wrapping instance to a FieldPropagator in order to avoid wasting time looking for uninteresting events. The wrapper will intercept the calls to the g function and to the eventOccurred method in order to ignore uninteresting events. The wrapped regular event detector will the see only the interesting events, i.e. either only events that occur when a user-provided event enabling predicate function is true, ignoring all events that occur when the event enabling predicate function is false. The number of calls to the g function will also be reduced.

Since:

12.0

See Also:

• FieldEventSlopeFilter

Constructor Summary

Constructors

Constructor	Description
FieldEventEnablingPredicateFilter(FieldEventDetectionSettings<T> detectionSettings, FieldEventDetector<T> rawDetector, FieldEnablingPredicate<T> enabler)	Constructor with full parameters.
FieldEventEnablingPredicateFilter(FieldEventDetector<T> rawDetector, FieldEnablingPredicate<T> enabler)	Wrap an event detector.

Method Summary

Modifier and Type	Method	Description
T	g(FieldSpacecraftState<T> s)	Compute the value of the switching function.
FieldEventDetectionSettings<T>	getDetectionSettings()	Getter for the settings.
FieldEventDetector<T>	getDetector()	Get the wrapped raw detector.
EventFunction	getEventFunction()	Get the event function.
FieldEventHandler<T>	getHandler()	Get the handler.
FieldEnablingPredicate<T>	getPredicate()	Getter for the enabling predicate.
void	init(FieldSpacecraftState<T> s0, FieldAbsoluteDate<T> t)	Initialize event detector at the start of a propagation.
boolean	isForward()	Check if the current propagation is forward or backward.
void	reset(FieldSpacecraftState<T> state, FieldAbsoluteDate<T> target)	Reset the event detector during propagation when the state is modified by an event or an additional data provider.
FieldEventEnablingPredicateFilter<T>	withDetectionSettings(FieldEventDetectionSettings<T> settings)	Builds a new instance from the input detection settings.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.propagation.events.FieldDetectorModifier

finish

Methods inherited from interface org.orekit.propagation.events.FieldEventDetector

getMaxCheckInterval, getMaxIterationCount, getThreshold

Constructor Details

FieldEventEnablingPredicateFilter

public FieldEventEnablingPredicateFilter(FieldEventDetector<T> rawDetector,
 FieldEnablingPredicate<T> enabler)

Wrap an event detector.

Parameters:

rawDetector - event detector to wrap

enabler - event enabling predicate function to use

FieldEventEnablingPredicateFilter

public FieldEventEnablingPredicateFilter(FieldEventDetectionSettings<T> detectionSettings,
 FieldEventDetector<T> rawDetector,
 FieldEnablingPredicate<T> enabler)

Constructor with full parameters.

Parameters:

detectionSettings - event detection settings

rawDetector - event detector to wrap

enabler - event enabling function to use

Since:

13.0

Method Details

withDetectionSettings

public FieldEventEnablingPredicateFilter<T> withDetectionSettings(FieldEventDetectionSettings<T> settings)

Builds a new instance from the input detection settings.

Parameters:

settings - event detection settings to be used

Returns:

a new detector

getDetector

public FieldEventDetector<T> getDetector()

Get the wrapped raw detector.

Specified by:

getDetector in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Returns:

the wrapped raw detector

getEventFunction

public EventFunction getEventFunction()

Get the event function. It defines g both for double and Field.

Specified by:

getEventFunction in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

getEventFunction in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Returns:

event function

getHandler

public FieldEventHandler<T> getHandler()

Get the handler.

Specified by:

getHandler in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

getHandler in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Returns:

event handler to call at event occurrences

getDetectionSettings

public FieldEventDetectionSettings<T> getDetectionSettings()

Getter for the settings.

Specified by:

getDetectionSettings in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

getDetectionSettings in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Returns:

detection settings

getPredicate

public FieldEnablingPredicate<T> getPredicate()

Getter for the enabling predicate.

Returns:

predicate

Since:

13.1

init

public void init(FieldSpacecraftState<T> s0,
 FieldAbsoluteDate<T> t)

Initialize event detector at the start of a propagation.

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

The default implementation initializes the handler.

Specified by:

init in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

init in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Parameters:

s0 - initial state

t - target time for the integration

reset

public void reset(FieldSpacecraftState<T> state,
 FieldAbsoluteDate<T> target)

Description copied from interface: FieldDetectorModifier

Reset the event detector during propagation when the state is modified by an event or an additional data provider.

The default implementation does nothing.

Specified by:

reset in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

reset in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Parameters:

state - current state

target - target time for the integration

g

public T g(FieldSpacecraftState<T> s)

Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

Specified by:

g in interface FieldDetectorModifier<T extends CalculusFieldElement<T>>

Specified by:

g in interface FieldEventDetector<T extends CalculusFieldElement<T>>

Parameters:

s - the current state information: date, kinematics, attitude

Returns:

value of the switching function

isForward

public boolean isForward()

Check if the current propagation is forward or backward.

Returns:

true if the current propagation is forward