org.orekit.propagation

## Interface Propagator

• ### Field Summary

Fields
Modifier and Type Field and Description
static double DEFAULT_MASS
Default mass.
• ### Method Summary

All 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.
<T extends EventDetector>void addEventDetector(T detector)
void clearEventsDetectors()
Remove all events detectors.
default void clearStepHandlers()
Remove all step handlers.
List<AdditionalStateProvider> getAdditionalStateProviders()
Get an unmodifiable list of providers for additional state.
AttitudeProvider getAttitudeProvider()
Get attitude provider.
static AttitudeProvider getDefaultLaw(Frames frames)
Get a default law using the given frames.
EphemerisGenerator getEphemerisGenerator()
Set up an ephemeris generator that will monitor the propagation for building an ephemeris from it once completed.
Collection<EventDetector> getEventsDetectors()
Get all the events detectors that have been added.
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.
StepHandlerMultiplexer getMultiplexer()
Get the multiplexer holding all step handlers.
boolean isAdditionalStateManaged(String name)
Check if an additional state is managed.
SpacecraftState propagate(AbsoluteDate target)
Propagate towards a target date.
SpacecraftState propagate(AbsoluteDate start, AbsoluteDate target)
Propagate from a start date towards a target date.
void resetInitialState(SpacecraftState state)
Reset the propagator initial state.
void setAttitudeProvider(AttitudeProvider attitudeProvider)
Set attitude provider.
default void setStepHandler(double h, OrekitFixedStepHandler handler)
Set a single handler for fixed stepsizes.
default void setStepHandler(OrekitStepHandler handler)
Set a single handler for variable stepsizes.
default MatricesHarvester setupMatricesComputation(String stmName, RealMatrix initialStm, DoubleArrayDictionary initialJacobianColumns)
Set up computation of State Transition Matrix and Jacobians matrix with respect to parameters.
• ### Methods inherited from interface org.orekit.utils.PVCoordinatesProvider

getPosition, getPVCoordinates
• ### Field Detail

• #### DEFAULT_MASS

static final double DEFAULT_MASS
Default mass.
Constant Field Values
• ### Method Detail

• #### getDefaultLaw

static AttitudeProvider getDefaultLaw(Frames frames)
Get a default law using the given frames.
Parameters:
frames - the set of frames to use.
Returns:
attitude law.
• #### getMultiplexer

StepHandlerMultiplexer getMultiplexer()
Get the multiplexer holding all step handlers.
Returns:
multiplexer holding all step handlers
Since:
11.0
• #### setStepHandler

default void setStepHandler(double h,
OrekitFixedStepHandler handler)
Set a single handler for fixed stepsizes.

This convenience method is equivalent to call getMultiplexer().clear() followed by getMultiplexer().add(h, handler)

Parameters:
h - fixed stepsize (s)
handler - handler called at the end of each finalized step
Since:
11.0
getMultiplexer(), StepHandlerMultiplexer.add(double, OrekitFixedStepHandler)
• #### setStepHandler

default void setStepHandler(OrekitStepHandler handler)
Set a single handler for variable stepsizes.

This convenience method is equivalent to call getMultiplexer().clear() followed by getMultiplexer().add(handler)

Parameters:
handler - handler called at the end of each finalized step
Since:
11.0
getMultiplexer(), StepHandlerMultiplexer.add(OrekitStepHandler)
• #### getEphemerisGenerator

EphemerisGenerator 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:

   EphemerisGenerator generator = propagator.getEphemerisGenerator();
propagator.propagate(target);
BoundedPropagator ephemeris = generator.getGeneratedEphemeris();

Returns:
ephemeris generator
• #### getInitialState

SpacecraftState getInitialState()
Get the propagator initial state.
Returns:
initial state
• #### resetInitialState

void resetInitialState(SpacecraftState state)
Reset the propagator initial state.
Parameters:
state - new initial state to consider

void addAdditionalStateProvider(AdditionalStateProvider additionalStateProvider)
Add a set of user-specified state parameters to be computed along with the orbit propagation.
Parameters:
additionalStateProvider - provider for additional state

List<AdditionalStateProvider> getAdditionalStateProviders()
Get an unmodifiable list of providers for additional state.
Returns:

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.

Parameters:
name - name of the additional state
Returns:
true if the additional state is managed

String[] getManagedAdditionalStates()
Get all the names of all managed states.
Returns:
names of all managed states

<T extends EventDetector> void addEventDetector(T detector)
Type Parameters:
T - class type for the generic version
Parameters:
detector - event detector to add
clearEventsDetectors(), getEventsDetectors()
• #### getAttitudeProvider

AttitudeProvider getAttitudeProvider()
Get attitude provider.
Returns:
attitude provider
• #### setAttitudeProvider

void setAttitudeProvider(AttitudeProvider attitudeProvider)
Set attitude provider.
Parameters:
attitudeProvider - attitude provider
• #### getFrame

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.

Returns:
frame in which the orbit is propagated
resetInitialState(SpacecraftState)
• #### setupMatricesComputation

default MatricesHarvester setupMatricesComputation(String stmName,
RealMatrix initialStm,
DoubleArrayDictionary initialJacobianColumns)
Set up computation of State Transition Matrix and Jacobians matrix with respect to parameters.

If this method is called, both State Transition Matrix and Jacobians with respect to the force models parameters that will be selected when propagation starts will be automatically computed, and the harvester will allow to retrieve them.

The arguments for initial matrices must be compatible with the orbit type and position angle that will be used by the propagator.

The default implementation throws an exception as the method is not supported by all propagators.

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
Since:
11.1
• #### propagate

SpacecraftState propagate(AbsoluteDate target)
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.

Parameters:
target - target date towards which orbit state should be propagated
Returns:
propagated state
• #### propagate

SpacecraftState propagate(AbsoluteDate start,
AbsoluteDate 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