Package org.orekit.propagation.analytical

Class Ephemeris

java.lang.Object

org.orekit.propagation.AbstractPropagator

org.orekit.propagation.analytical.AbstractAnalyticalPropagator

org.orekit.propagation.analytical.Ephemeris

All Implemented Interfaces:

BoundedPropagator, Propagator, PVCoordinatesProvider

public class Ephemeris
extends AbstractAnalyticalPropagator
implements BoundedPropagator

This class is designed to accept and handle tabulated orbital entries. Tabulated entries are classified and then extrapolated in way to obtain continuous output, with accuracy and computation methods configured by the user.

Author:

Fabien Maussion, Véronique Pommier-Maurussane, Luc Maisonobe, Vincent Cucchietti

Field Summary

Fields inherited from interface org.orekit.propagation.Propagator

DEFAULT_MASS

Constructor Summary

Constructors

Constructor	Description
Ephemeris(List<SpacecraftState> states, int interpolationPoints)	Legacy constructor with tabulated states and default Hermite interpolation.
Ephemeris(List<SpacecraftState> states, TimeInterpolator<SpacecraftState> stateInterpolator)	Constructor with tabulated states.
Ephemeris(List<SpacecraftState> states, TimeInterpolator<SpacecraftState> stateInterpolator, List<StateCovariance> covariances, TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator)	Constructor with tabulated states and associated covariances.
Ephemeris(List<SpacecraftState> states, TimeInterpolator<SpacecraftState> stateInterpolator, List<StateCovariance> covariances, TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator, AttitudeProvider attitudeProvider)	Constructor with tabulated states and associated covariances.
Ephemeris(List<SpacecraftState> states, TimeInterpolator<SpacecraftState> stateInterpolator, AttitudeProvider attitudeProvider)	Constructor with tabulated states.

Method Summary

Modifier and Type	Method	Description
SpacecraftState	basicPropagate(AbsoluteDate date)	Propagate an orbit without any fancy features.
static void	checkInputConsistency(List<SpacecraftState> states, TimeInterpolator<SpacecraftState> stateInterpolator, List<StateCovariance> covariances, TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator)	Check input consistency between states, covariances and their associated interpolators.
static void	checkStatesAndCovariancesConsistency(List<SpacecraftState> states, List<StateCovariance> covariances)	Check that given states and covariances are consistent.
protected AbstractMatricesHarvester	createHarvester(String stmName, RealMatrix initialStm, DoubleArrayDictionary initialJacobianColumns)	Create the harvester suitable for propagator.
Optional<StateCovariance>	getCovariance(AbsoluteDate date)	Get the covariance at given date.
Optional<TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>>>	getCovarianceInterpolator()	Get covariance interpolator.
Frame	getFrame()	Get the frame in which the orbit is propagated.
SpacecraftState	getInitialState()	Get the propagator initial state.
String[]	getManagedAdditionalStates()	Get all the names of all managed states.
protected double	getMass(AbsoluteDate date)	Get the mass.
AbsoluteDate	getMaxDate()	Get the last date of the range.
AbsoluteDate	getMinDate()	Get the first date of the range.
TimeInterpolator<SpacecraftState>	getStateInterpolator()	Get state interpolator.
boolean	isAdditionalStateManaged(String name)	Check if an additional state is managed.
protected Orbit	propagateOrbit(AbsoluteDate date)	Extrapolate an orbit up to a specific target date.
void	resetInitialState(SpacecraftState state)	Try (and fail) to reset the initial state.
protected void	resetIntermediateState(SpacecraftState state, boolean forward)	Reset an intermediate state.

Methods inherited from class org.orekit.propagation.analytical.AbstractAnalyticalPropagator

acceptStep, addEventDetector, clearEventsDetectors, getEphemerisGenerator, getEventsDetectors, getJacobiansColumnsNames, getPvProvider, propagate

Methods inherited from class org.orekit.propagation.AbstractPropagator

addAdditionalStateProvider, getAdditionalStateProviders, getAttitudeProvider, getHarvester, getMultiplexer, getStartDate, initializeAdditionalStates, initializePropagation, propagate, setAttitudeProvider, setStartDate, setupMatricesComputation, 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.Propagator

addAdditionalStateProvider, addEventDetector, clearEventsDetectors, clearStepHandlers, getAdditionalStateProviders, getAttitudeProvider, getEphemerisGenerator, getEventsDetectors, getMultiplexer, getPosition, getPVCoordinates, propagate, propagate, setAttitudeProvider, setStepHandler, setStepHandler, setupMatricesComputation

Constructor Detail

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 int interpolationPoints)
          throws MathIllegalArgumentException

Legacy constructor with tabulated states and default Hermite interpolation.

As this implementation of interpolation is polynomial, it should be used only with small samples (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Parameters:

states - list of spacecraft states

interpolationPoints - number of points to use in interpolation

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

OrekitIllegalArgumentException - if states are not defined the same way (orbit or absolute position-velocity-acceleration)

See Also:

Ephemeris(List, TimeInterpolator, List, TimeInterpolator), SpacecraftStateInterpolator

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 TimeInterpolator<SpacecraftState> stateInterpolator)
          throws MathIllegalArgumentException

Constructor with tabulated states.

Parameters:

states - list of spacecraft states

stateInterpolator - spacecraft state interpolator

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

OrekitIllegalArgumentException - if states are not defined the same way (orbit or absolute position-velocity-acceleration)

See Also:

Ephemeris(List, TimeInterpolator, List, TimeInterpolator)

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 TimeInterpolator<SpacecraftState> stateInterpolator,
                 AttitudeProvider attitudeProvider)
          throws MathIllegalArgumentException

Constructor with tabulated states.

Parameters:

states - list of spacecraft states

stateInterpolator - spacecraft state interpolator

attitudeProvider - attitude law to use, null by default

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

OrekitIllegalArgumentException - if states are not defined the same way (orbit or absolute position-velocity-acceleration)

See Also:

Ephemeris(List, TimeInterpolator, List, TimeInterpolator)

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 TimeInterpolator<SpacecraftState> stateInterpolator,
                 List<StateCovariance> covariances,
                 TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator)
          throws MathIllegalArgumentException

Constructor with tabulated states and associated covariances.

Parameters:

states - list of spacecraft states

stateInterpolator - spacecraft state interpolator

covariances - tabulated covariances associated to tabulated states ephemeris bounds to be doing extrapolation

covarianceInterpolator - covariance interpolator

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

OrekitIllegalArgumentException - if states are not defined the same way (orbit or absolute position-velocity-acceleration)

OrekitIllegalArgumentException - if number of states is different from the number of covariances

OrekitIllegalStateException - if dates between states and associated covariances are different

Since:

9.0

See Also:

Ephemeris(List, TimeInterpolator, List, TimeInterpolator, AttitudeProvider)

Ephemeris

public Ephemeris(List<SpacecraftState> states,
                 TimeInterpolator<SpacecraftState> stateInterpolator,
                 List<StateCovariance> covariances,
                 TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator,
                 AttitudeProvider attitudeProvider)
          throws MathIllegalArgumentException

Constructor with tabulated states and associated covariances.

The user is expected to explicitly define an attitude provider if they want to use one. Otherwise, it is null by default

Parameters:

states - list of spacecraft states

stateInterpolator - spacecraft state interpolator

covariances - tabulated covariances associated to tabulated states

covarianceInterpolator - covariance interpolator

attitudeProvider - attitude law to use, null by default

Throws:

MathIllegalArgumentException - if the number of states is smaller than the number of points to use in interpolation

OrekitIllegalArgumentException - if states are not defined the same way (orbit or absolute position-velocity-acceleration)

OrekitIllegalArgumentException - if number of states is different from the number of covariances

OrekitIllegalStateException - if dates between states and associated covariances are different

Since:

10.1

Method Detail

checkInputConsistency

public static void checkInputConsistency(List<SpacecraftState> states,
                                         TimeInterpolator<SpacecraftState> stateInterpolator,
                                         List<StateCovariance> covariances,
                                         TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>> covarianceInterpolator)

Check input consistency between states, covariances and their associated interpolators.

Parameters:

states - spacecraft states sample

stateInterpolator - spacecraft state interpolator

covariances - covariances sample

covarianceInterpolator - covariance interpolator

checkStatesAndCovariancesConsistency

public static void checkStatesAndCovariancesConsistency(List<SpacecraftState> states,
                                                        List<StateCovariance> covariances)

Check that given states and covariances are consistent.

Parameters:

states - tabulates states to check

covariances - tabulated covariances associated to tabulated states to check

getMinDate

public AbsoluteDate getMinDate()

Get the first date of the range.

Specified by:

getMinDate in interface BoundedPropagator

Returns:

the first date of the range

getMaxDate

public AbsoluteDate getMaxDate()

Get the last date of the range.

Specified by:

getMaxDate in interface BoundedPropagator

Returns:

the last date of the range

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

Overrides:

getFrame in class AbstractPropagator

Returns:

frame in which the orbit is propagated

See Also:

Propagator.resetInitialState(SpacecraftState)

getCovariance

public Optional<StateCovariance> getCovariance(AbsoluteDate date)

Get the covariance at given date.

BEWARE : If this instance has been created without sample of covariances and/or with spacecraft states defined with absolute position-velocity-acceleration, it will return an empty Optional.

Parameters:

date - date at which the covariance is desired

Returns:

covariance at given date

See Also:

Optional

basicPropagate

public SpacecraftState basicPropagate(AbsoluteDate date)

Propagate an orbit without any fancy features.

This method is similar in spirit to the AbstractAnalyticalPropagator.propagate(org.orekit.time.AbsoluteDate, org.orekit.time.AbsoluteDate) 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.

Overrides:

basicPropagate in class AbstractAnalyticalPropagator

Parameters:

date - target date for propagation

Returns:

state at specified date

propagateOrbit

protected Orbit propagateOrbit(AbsoluteDate date)

Extrapolate an orbit up to a specific target date.

Specified by:

propagateOrbit in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

extrapolated parameters

getMass

protected double getMass(AbsoluteDate date)

Get the mass.

Specified by:

getMass in class AbstractAnalyticalPropagator

Parameters:

date - target date for the orbit

Returns:

mass mass

resetInitialState

public void resetInitialState(SpacecraftState state)

Try (and fail) to reset the initial state.

This method always throws an exception, as ephemerides cannot be reset.

Specified by:

resetInitialState in interface Propagator

Overrides:

resetInitialState in class AbstractPropagator

Parameters:

state - new initial state to consider

resetIntermediateState

protected void resetIntermediateState(SpacecraftState state,
                                      boolean forward)

Reset an intermediate state.

Specified by:

resetIntermediateState in class AbstractAnalyticalPropagator

Parameters:

state - new intermediate state to consider

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

getInitialState

public SpacecraftState getInitialState()

Get the propagator initial state.

Specified by:

getInitialState in interface Propagator

Overrides:

getInitialState in class AbstractPropagator

Returns:

initial state

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 a provider has been registered by calling the addAdditionalStateProvider method.

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 are piecewise constant between state resets that may change them if some event handler resetState method is called at an event occurrence and happens to change the unmanaged additional state.

Specified by:

isAdditionalStateManaged in interface Propagator

Overrides:

isAdditionalStateManaged in class AbstractPropagator

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

Overrides:

getManagedAdditionalStates in class AbstractPropagator

Returns:

names of all managed states

createHarvester

protected AbstractMatricesHarvester createHarvester(String stmName,
                                                    RealMatrix initialStm,
                                                    DoubleArrayDictionary initialJacobianColumns)

Create the harvester suitable for propagator.

Overrides:

createHarvester in class AbstractPropagator

Parameters:

stmName - State Transition Matrix state name

initialStm - initial State Transition Matrix ∂Y/∂Y₀, if null (which is the most frequent case), assumed to be 6x6 identity

initialJacobianColumns - initial columns of the Jacobians matrix with respect to parameters, if null or if some selected parameters are missing from the dictionary, the corresponding initial column is assumed to be 0

Returns:

harvester to retrieve computed matrices during and after propagation

getStateInterpolator

public TimeInterpolator<SpacecraftState> getStateInterpolator()

Get state interpolator.

Returns:

state interpolator

getCovarianceInterpolator

public Optional<TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>>> getCovarianceInterpolator()

Get covariance interpolator.

Returns:

optional covariance interpolator

See Also:

Optional