org.orekit.propagation
Class AbstractPropagator

java.lang.Object
  org.orekit.propagation.AbstractPropagator

All Implemented Interfaces:

java.io.Serializable, BasicPropagator, Propagator, PVCoordinatesProvider

Direct Known Subclasses:

EcksteinHechlerPropagator, KeplerianPropagator

public abstract class AbstractPropagator
extends java.lang.Object
implements Propagator

Common handling of Propagator methods for analytical-like 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. Only three methods must be implemented by derived classes: getInitialState(), basicPropagate(AbsoluteDate) and Propagator.resetInitialState(SpacecraftState). The second method should perform straightforward propagation starting from some internally stored initial state up to the specified target date. The third method should reset the initial state when called.

Version:

$Revision: 3123 $ $Date: 2010-02-15 17:18:40 +0100 (lun. 15 févr. 2010) $

Author:

Luc Maisonobe

See Also:

Serialized Form

Field Summary

Fields inherited from interface org.orekit.propagation.Propagator

EPHEMERIS_GENERATION_MODE, MASTER_MODE, SLAVE_MODE

Constructor Summary

protected

AbstractPropagator() Build a new instance.

Method Summary

protected CombinedEventsDetectorsManager	addEndDateChecker(AbsoluteDate startDate, AbsoluteDate endDate, CombinedEventsDetectorsManager manager) Add an event handler for end date checking.
void	addEventDetector(EventDetector detector) Add an event detector.
protected abstract SpacecraftState	basicPropagate(AbsoluteDate date) Propagate an orbit without any fancy features.
void	clearEventsDetectors() Remove all events detectors.
java.util.Collection<EventDetector>	getEventsDetectors() Get all the events detectors that have been added.
BoundedPropagator	getGeneratedEphemeris() Get the ephemeris generated during propagation.
abstract SpacecraftState	getInitialState() Get the propagator initial state.
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.
SpacecraftState	propagate(AbsoluteDate target) Propagate towards a target date.
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.

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

resetInitialState

Constructor Detail

AbstractPropagator

protected AbstractPropagator()

Build a new instance.

Method Detail

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()

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

getGeneratedEphemeris

public BoundedPropagator getGeneratedEphemeris()

Get the ephemeris generated during propagation.

Specified by:

getGeneratedEphemeris in interface Propagator

Returns:

generated ephemeris

See Also:

Propagator.setEphemerisMode()

addEventDetector

public void addEventDetector(EventDetector detector)

Add an event detector.

Specified by:

addEventDetector in interface Propagator

Parameters:

detector - event detector to add

See Also:

Propagator.clearEventsDetectors(), Propagator.getEventsDetectors()

getEventsDetectors

public java.util.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 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 like the ones implemented the extended interface Propagator 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 BasicPropagator

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

getInitialState

public abstract SpacecraftState getInitialState()

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Returns:

initial state

basicPropagate

protected abstract SpacecraftState basicPropagate(AbsoluteDate date)
                                           throws PropagationException

Propagate an orbit without any fancy features.

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

Parameters:

date - target date for propagation

Returns:

state at specified date

Throws:

PropagationException - if propagation cannot reach specified date

addEndDateChecker

protected CombinedEventsDetectorsManager addEndDateChecker(AbsoluteDate startDate,
                                                           AbsoluteDate endDate,
                                                           CombinedEventsDetectorsManager manager)

Add an event handler for end date checking.

This method can be used to simplify handling of integration end date. It leverages the nominal stop condition with the exceptional stop conditions.

Parameters:

startDate - propagation start date

endDate - desired end date

manager - manager containing the user-defined handlers

Returns:

a new manager containing all the user-defined handlers plus a dedicated manager triggering a stop event at entDate