org.orekit.propagation

Class AbstractPropagator

java.lang.Object

org.orekit.propagation.AbstractPropagator

All Implemented Interfaces:

Propagator, PVCoordinatesProvider

Direct Known Subclasses:

AbstractAnalyticalPropagator, AbstractIntegratedPropagator

public abstract class AbstractPropagator
extends Object
implements Propagator

Common handling of Propagator methods for analytical propagators.

This abstract class allows to provide easily the full set of Propagator methods, including all propagation modes support and discrete events support for any simple propagation method.

Author:

Luc Maisonobe

Field Summary

Fields inherited from interface org.orekit.propagation.Propagator

DEFAULT_LAW, DEFAULT_MASS, EPHEMERIS_GENERATION_MODE, MASTER_MODE, SLAVE_MODE

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractPropagator() Build a new instance.

Method Summary

Methods

Modifier and Type	Method and Description
void	addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider) Add a set of user-specified state parameters to be computed along with the orbit propagation.
abstract <T extends EventDetector> void	addEventDetector(T detector) Add an event detector.
abstract void	clearEventsDetectors() Remove all events detectors.
List<AdditionalStateProvider>	getAdditionalStateProviders() Get an unmodifiable list of providers for additional state.
AttitudeProvider	getAttitudeProvider() Get attitude provider.
abstract Collection<EventDetector>	getEventsDetectors() Get all the events detectors that have been added.
protected double	getFixedStepSize() Get the fixed step size.
Frame	getFrame() Get the frame in which the orbit is propagated.
abstract BoundedPropagator	getGeneratedEphemeris() Get the ephemeris generated during propagation.
SpacecraftState	getInitialState() Get the propagator initial state.
String[]	getManagedAdditionalStates() Get all the names of all managed states.
int	getMode() Get the current operating mode of the propagator.
PVCoordinates	getPVCoordinates(AbsoluteDate date, Frame frame) Get the PVCoordinates of the body in the selected frame.
protected AbsoluteDate	getStartDate() Get the start date.
protected OrekitStepHandler	getStepHandler() Get the step handler.
boolean	isAdditionalStateManaged(String name) Check if an additional state is managed.
SpacecraftState	propagate(AbsoluteDate target) Propagate towards a target date.
void	resetInitialState(SpacecraftState state) Reset the propagator initial state.
void	setAttitudeProvider(AttitudeProvider attitudeProvider) Set attitude provider.
void	setEphemerisMode() Set the propagator to ephemeris generation mode.
void	setMasterMode(double h, OrekitFixedStepHandler handler) Set the propagator to master mode with fixed steps.
void	setMasterMode(OrekitStepHandler handler) Set the propagator to master mode with variable steps.
void	setSlaveMode() Set the propagator to slave mode.
protected void	setStartDate(AbsoluteDate startDate) Set a start date.
protected SpacecraftState	updateAdditionalStates(SpacecraftState original) Update state by adding all additional states.

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.Propagator

propagate

Constructor Detail

AbstractPropagator

protected AbstractPropagator()

Build a new instance.

Method Detail

setStartDate

protected void setStartDate(AbsoluteDate startDate)

Set a start date.

Parameters:

startDate - start date

getStartDate

protected AbsoluteDate getStartDate()

Get the start date.

Returns:

start date

getAttitudeProvider

public AttitudeProvider getAttitudeProvider()

Get attitude provider.

Specified by:

getAttitudeProvider in interface Propagator

Returns:

attitude provider

setAttitudeProvider

public void setAttitudeProvider(AttitudeProvider attitudeProvider)

Set attitude provider.

Specified by:

setAttitudeProvider in interface Propagator

Parameters:

attitudeProvider - attitude provider

getInitialState

public SpacecraftState getInitialState()
                                throws PropagationException

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Returns:

initial state

Throws:

PropagationException - if state cannot be retrieved

getMode

public int getMode()

Get the current operating mode of the propagator.

Specified by:

getMode in interface Propagator

Returns:

one of Propagator.SLAVE_MODE, Propagator.MASTER_MODE, Propagator.EPHEMERIS_GENERATION_MODE

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode()

getFrame

public Frame getFrame()

Get the frame in which the orbit is propagated.

The propagation frame is the definition frame of the initial state, so this method should be called after this state has been set, otherwise it may return null.

Specified by:

getFrame in interface Propagator

Returns:

frame in which the orbit is propagated

See Also:

Propagator.resetInitialState(SpacecraftState)

resetInitialState

public void resetInitialState(SpacecraftState state)
                       throws PropagationException

Reset the propagator initial state.

Specified by:

resetInitialState in interface Propagator

Parameters:

state - new initial state to consider

Throws:

PropagationException - if initial state cannot be reset

setSlaveMode

public void setSlaveMode()

Set the propagator to slave mode.

This mode is used when the user needs only the final orbit at the target time. The (slave) propagator computes this result and return it to the calling (master) application, without any intermediate feedback.

This is the default mode.

Specified by:

setSlaveMode in interface Propagator

See Also:

Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.SLAVE_MODE

setMasterMode

public void setMasterMode(double h,
                 OrekitFixedStepHandler handler)

Set the propagator to master mode with fixed steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Specified by:

setMasterMode in interface Propagator

Parameters:

h - fixed stepsize (s)

handler - handler called at the end of each finalized step

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(OrekitStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.MASTER_MODE

setMasterMode

public void setMasterMode(OrekitStepHandler handler)

Set the propagator to master mode with variable steps.

This mode is used when the user needs to have some custom function called at the end of each finalized step during integration. The (master) propagator integration loop calls the (slave) application callback methods at each finalized step.

Specified by:

setMasterMode in interface Propagator

Parameters:

handler - handler called at the end of each finalized step

See Also:

Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setEphemerisMode(), Propagator.getMode(), Propagator.MASTER_MODE

setEphemerisMode

public void setEphemerisMode()

Set the propagator to ephemeris generation mode.

This mode is used when the user needs random access to the orbit state at any time between the initial and target times, and in no sequential order. 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.

Beware that since this mode stores all intermediate results, it may be memory intensive for long integration ranges and high precision/short time steps.

Specified by:

setEphemerisMode in interface Propagator

See Also:

Propagator.getGeneratedEphemeris(), Propagator.setSlaveMode(), Propagator.setMasterMode(double, OrekitFixedStepHandler), Propagator.setMasterMode(OrekitStepHandler), Propagator.getMode(), Propagator.EPHEMERIS_GENERATION_MODE

addAdditionalStateProvider

public void addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider)
                                throws OrekitException

Add a set of user-specified state parameters to be computed along with the orbit propagation.

Specified by:

addAdditionalStateProvider in interface Propagator

Parameters:

additionalStateProvider - provider for additional state

Throws:

OrekitException - if an additional state with the same name is already present

getAdditionalStateProviders

public List<AdditionalStateProvider> getAdditionalStateProviders()

Get an unmodifiable list of providers for additional state.

Specified by:

getAdditionalStateProviders in interface Propagator

Returns:

providers for the additional states

updateAdditionalStates

protected SpacecraftState updateAdditionalStates(SpacecraftState original)
                                          throws PropagationException

Update state by adding all additional states.

Parameters:

original - original state

Returns:

updated state, with all additional states included

Throws:

PropagationException - if one of the providers throws one

See Also:

addAdditionalStateProvider(AdditionalStateProvider)

isAdditionalStateManaged

public boolean isAdditionalStateManaged(String name)

Check if an additional state is managed.

Managed states are states for which the propagators know how to compute its evolution. They correspond to additional states for which an additional state provider has been registered by calling the addAdditionalStateProvider method. If the propagator is an integrator-based propagator, the states for which a set of additional equations has been registered by calling the addAdditionalEquations method are also counted as managed additional states.

Additional states that are present in the initial state but have no evolution method registered are not considered as managed states. These unmanaged additional states are not lost during propagation, though. Their value will simply be copied unchanged throughout propagation.

Specified by:

isAdditionalStateManaged in interface Propagator

Parameters:

name - name of the additional state

Returns:

true if the additional state is managed

getManagedAdditionalStates

public String[] getManagedAdditionalStates()

Get all the names of all managed states.

Specified by:

getManagedAdditionalStates in interface Propagator

Returns:

names of all managed states

getFixedStepSize

protected double getFixedStepSize()

Get the fixed step size.

Returns:

fixed step size (or NaN if there are no fixed step size).

getStepHandler

protected OrekitStepHandler getStepHandler()

Get the step handler.

Returns:

step handler

getGeneratedEphemeris

public abstract BoundedPropagator getGeneratedEphemeris()

Get the ephemeris generated during propagation.

Specified by:

getGeneratedEphemeris in interface Propagator

Returns:

generated ephemeris

See Also:

Propagator.setEphemerisMode()

addEventDetector

public abstract <T extends EventDetector> void addEventDetector(T detector)

Add an event detector.

Specified by:

addEventDetector in interface Propagator

Type Parameters:

T - class type for the generic version

Parameters:

detector - event detector to add

See Also:

Propagator.clearEventsDetectors(), Propagator.getEventsDetectors()

getEventsDetectors

public abstract Collection<EventDetector> getEventsDetectors()

Get all the events detectors that have been added.

Specified by:

getEventsDetectors in interface Propagator

Returns:

an unmodifiable collection of the added detectors

See Also:

Propagator.addEventDetector(EventDetector), Propagator.clearEventsDetectors()

clearEventsDetectors

public abstract void clearEventsDetectors()

Remove all events detectors.

Specified by:

clearEventsDetectors in interface Propagator

See Also:

Propagator.addEventDetector(EventDetector), Propagator.getEventsDetectors()

propagate

public SpacecraftState propagate(AbsoluteDate target)
                          throws PropagationException

Propagate towards a target date.

Simple propagators use only the target date as the specification for computing the propagated state. More feature rich propagators can consider other information and provide different operating modes or G-stop facilities to stop at pinpointed events occurrences. In these cases, the target date is only a hint, not a mandatory objective.

Specified by:

propagate in interface Propagator

Parameters:

target - target date towards which orbit state should be propagated

Returns:

propagated state

Throws:

PropagationException - if state cannot be propagated

getPVCoordinates

public PVCoordinates getPVCoordinates(AbsoluteDate date,
                             Frame frame)
                               throws OrekitException

Get the PVCoordinates of the body in the selected frame.

Specified by:

getPVCoordinates in interface PVCoordinatesProvider

Parameters:

date - current date

frame - the frame where to define the position

Returns:

position/velocity of the body (m and m/s)

Throws:

OrekitException - if position cannot be computed in given frame