org.orekit.propagation.analytical

Class FieldAbstractAnalyticalPropagator<T extends CalculusFieldElement<T>>

java.lang.Object

org.orekit.propagation.FieldAbstractPropagator<T>

org.orekit.propagation.analytical.FieldAbstractAnalyticalPropagator<T>

All Implemented Interfaces:

FieldPropagator<T>, FieldPVCoordinatesProvider<T>

Direct Known Subclasses:

FieldBrouwerLyddanePropagator, FieldEcksteinHechlerPropagator, FieldIntegratedEphemeris, FieldKeplerianPropagator, FieldTLEPropagator

public abstract class FieldAbstractAnalyticalPropagator<T extends CalculusFieldElement<T>>
extends FieldAbstractPropagator<T>

Common handling of FieldPropagator methods for analytical propagators.

This abstract class allows to provide easily the full set of FieldPropagator methods, including all propagation modes support and discrete events support for any simple propagation method. Only two methods must be implemented by derived classes: propagateOrbit(FieldAbsoluteDate, CalculusFieldElement[]) and getMass(FieldAbsoluteDate). The first method should perform straightforward propagation starting from some internally stored initial state up to the specified target date.

Author:

Luc Maisonobe

Field Summary

Fields inherited from interface org.orekit.propagation.FieldPropagator

DEFAULT_MASS

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FieldAbstractAnalyticalPropagator(Field<T> field, AttitudeProvider attitudeProvider) Build a new instance.

Method Summary

Modifier and Type	Method and Description
protected FieldSpacecraftState<T>	acceptStep(org.orekit.propagation.analytical.FieldAbstractAnalyticalPropagator.FieldBasicStepInterpolator interpolator, FieldAbsoluteDate<T> target) Accept a step, triggering events and step handlers.
<D extends FieldEventDetector<T>> void	addEventDetector(D detector) Add an event detector.
protected FieldSpacecraftState<T>	basicPropagate(FieldAbsoluteDate<T> date) Propagate an orbit without any fancy features.
void	clearEventsDetectors() Remove all events detectors.
FieldEphemerisGenerator<T>	getEphemerisGenerator() Set up an ephemeris generator that will monitor the propagation for building an ephemeris from it once completed.
Collection<FieldEventDetector<T>>	getEventsDetectors() Get all the events detectors that have been added.
protected abstract T	getMass(FieldAbsoluteDate<T> date) Get the mass.
T[]	getParameters(Field<T> field) Get model parameters.
protected abstract List<ParameterDriver>	getParametersDrivers() Get the parameters driver for propagation model.
FieldPVCoordinatesProvider<T>	getPvProvider() Get PV coordinates provider.
FieldSpacecraftState<T>	propagate(FieldAbsoluteDate<T> start, FieldAbsoluteDate<T> target) Propagate from a start date towards a target date.
protected abstract FieldOrbit<T>	propagateOrbit(FieldAbsoluteDate<T> date, T[] parameters) Extrapolate an orbit up to a specific target date.
protected abstract void	resetIntermediateState(FieldSpacecraftState<T> state, boolean forward) Reset an intermediate state.

Methods inherited from class org.orekit.propagation.FieldAbstractPropagator

addAdditionalStateProvider, getAdditionalStateProviders, getAttitudeProvider, getField, getFrame, getInitialState, getManagedAdditionalStates, getMultiplexer, getPVCoordinates, getStartDate, initializeAdditionalStates, initializePropagation, isAdditionalStateManaged, propagate, resetInitialState, setAttitudeProvider, setStartDate, stateChanged, updateAdditionalStates, updateUnmanagedStates

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.FieldPropagator

clearStepHandlers, setStepHandler, setStepHandler

Constructor Detail

FieldAbstractAnalyticalPropagator

protected FieldAbstractAnalyticalPropagator(Field<T> field,
                                            AttitudeProvider attitudeProvider)

Build a new instance.

Parameters:

attitudeProvider - provider for attitude computation

field - field used as default

Method Detail

getEphemerisGenerator

public FieldEphemerisGenerator<T> getEphemerisGenerator()

Set up an ephemeris generator that will monitor the propagation for building an ephemeris from it once completed.

This generator can be used when the user needs fast random access to the orbit state at any time between the initial and target times. A typical example is the implementation of search and iterative algorithms that may navigate forward and backward inside the propagation range before finding their result even if the propagator used is integration-based and only goes from one initial time to one target time.

Beware that when used with integration-based propagators, the generator will store all intermediate results. It is therefore memory intensive for long integration-based ranges and high precision/short time steps. When used with analytical propagators, the generator only stores start/stop time and a reference to the analytical propagator itself to call it back as needed, so it is less memory intensive.

The returned ephemeris generator will be initially empty, it will be filled with propagation data when a subsequent call to either propagate(target) or propagate(start, target) is called. The proper way to use this method is therefore to do:

   FieldEphemerisGenerator<T> generator = propagator.getEphemerisGenerator();
   propagator.propagate(target);
   FieldBoundedPropagator<T> ephemeris = generator.getGeneratedEphemeris();
 

Returns:

ephemeris generator

addEventDetector

public <D extends FieldEventDetector<T>> void addEventDetector(D detector)

Add an event detector.

Type Parameters:

D - class type for the generic version

Parameters:

detector - event detector to add

See Also:

FieldPropagator.clearEventsDetectors(), FieldPropagator.getEventsDetectors()

getEventsDetectors

public Collection<FieldEventDetector<T>> getEventsDetectors()

Get all the events detectors that have been added.

Returns:

an unmodifiable collection of the added detectors

See Also:

FieldPropagator.addEventDetector(FieldEventDetector), FieldPropagator.clearEventsDetectors()

clearEventsDetectors

public void clearEventsDetectors()

Remove all events detectors.

See Also:

FieldPropagator.addEventDetector(FieldEventDetector), FieldPropagator.getEventsDetectors()

propagate

public FieldSpacecraftState<T> propagate(FieldAbsoluteDate<T> start,
                                         FieldAbsoluteDate<T> target)

Propagate from a start date towards a target date.

Those propagators use a start date and a target date to compute the propagated state. For propagators using event detection mechanism, if the provided start date is different from the initial state date, a first, simple propagation is performed, without processing any event computation. Then complete propagation is performed from start date to target date.

Parameters:

start - start date from which orbit state should be propagated

target - target date to which orbit state should be propagated

Returns:

propagated state

acceptStep

protected FieldSpacecraftState<T> acceptStep(org.orekit.propagation.analytical.FieldAbstractAnalyticalPropagator.FieldBasicStepInterpolator interpolator,
                                             FieldAbsoluteDate<T> target)
                                      throws MathRuntimeException

Accept a step, triggering events and step handlers.

Parameters:

interpolator - interpolator for the current step

target - final propagation time

Returns:

state at the end of the step

Throws:

MathRuntimeException - if an event cannot be located

getMass

protected abstract T getMass(FieldAbsoluteDate<T> date)

Get the mass.

Parameters:

date - target date for the orbit

Returns:

mass mass

getPvProvider

public FieldPVCoordinatesProvider<T> getPvProvider()

Get PV coordinates provider.

Returns:

PV coordinates provider

resetIntermediateState

protected abstract void resetIntermediateState(FieldSpacecraftState<T> state,
                                               boolean forward)

Reset an intermediate state.

Parameters:

state - new intermediate state to consider

forward - if true, the intermediate state is valid for propagations after itself

propagateOrbit

protected abstract FieldOrbit<T> propagateOrbit(FieldAbsoluteDate<T> date,
                                                T[] parameters)

Extrapolate an orbit up to a specific target date.

Parameters:

date - target date for the orbit

parameters - model parameters

Returns:

extrapolated parameters

getParametersDrivers

protected abstract List<ParameterDriver> getParametersDrivers()

Get the parameters driver for propagation model.

Returns:

drivers for propagation model

getParameters

public T[] getParameters(Field<T> field)

Get model parameters.

Parameters:

field - field to which the elements belong

Returns:

model parameters

basicPropagate

protected FieldSpacecraftState<T> basicPropagate(FieldAbsoluteDate<T> date)

Propagate an orbit without any fancy features.

This method is similar in spirit to the propagate(org.orekit.time.FieldAbsoluteDate<T>, org.orekit.time.FieldAbsoluteDate<T>) method, except that it does not call any handler during propagation, nor any discrete events, not additional states. It always stop exactly at the specified date.

Parameters:

date - target date for propagation

Returns:

state at specified date