agi.foundation.propagators

(agi.foundation.models-2024r3.jar)

Class StateTransitionMatrix

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.propagators.advanced.PropagationStateElement

agi.foundation.propagators.StateTransitionMatrix

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public class StateTransitionMatrix
extends PropagationStateElement

An extended state transition matrix, if consider parameters are not used then it functions as a normal state transition matrix: mapping the value of the state parameters from one time to another time.

The state transition matrix represents the transformation from the state at one time to the state at another time. This can be used as an alternative to propagating a state in time with NumericalPropagator, but is more often used in order to find the time-varying covariance of the state. This is because the construction of a StateTransitionMatrix entails the linearization of the state, and in most cases calculating the derivatives of the state transition matrix takes as long or longer as calculating the derivatives of the state.

To find the covariance of a state over time a StateTransitionMatrix is propagated with a NumericalPropagator and the resulting data is used to create the covariance information for the same period using StateTransitionMatrix.populateCovarianceCollection(agi.foundation.coordinates.Matrix, agi.foundation.DateMotionCollection1<agi.foundation.coordinates.Matrix>, agi.foundation.propagators.TransitionType).

If consider parameters are used, then this class represents information in the following form:

If the cumulative dimension of the state elements is N, and the cumulative dimension of the consider parameters is M, then Φ is an ordinary state transition matrix: an NxN matrix equal to the partials of the state at time t_j with respect to the state at time t_i. Θ is an NxM matrix equal to the partials of the state at time t_j with respect to the consider parameters at time t_i, and the zero and identity matrices are size MxN and MxM, respectively. The complete consider covariance matrix is a square matrix with a dimension of N+M.

Constructor Summary

Constructors

Modifier	Constructor and Description
	StateTransitionMatrix() Initializes a new instance.
protected	StateTransitionMatrix(StateTransitionMatrix existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
void	addConsiderParameter(IPartialDifferentiable considerParameter) Adds a consider parameter to the StateTransitionMatrix.
void	addStateParameter(IPartialDifferentiable stateParameter, IPartialDifferentiable stateDerivative) Adds a state parameter to the StateTransitionMatrix.
protected boolean	checkForSameDefinition(PropagationStateElement other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(StateTransitionMatrix other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
void	enumerateDependencies(DependencyEnumerator enumerator) Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon.
protected void	freezeAggregatedObjects() Called by DefinitionalObject.freeze() to also freeze any objects that are considered to be a part of this object.
int	getConsiderDimension() Gets the summed dimension of all of the consider parameters.
IPartialDifferentiable	getConsiderParameter(int index) Gets the consider parameter at the specified index which has been added to this StateTransitionMatrix.
PropagationStateElementConverter	getConverter(EvaluatorGroup group, Motion1<int[]> stateInputIndices) Gets an instance of an output type which can convert the output of propagation back into the native type of this state element.
PropagationStateElementEvaluator	getDerivatives(EvaluatorGroup group) This is used by the NumericalPropagatorDefinition to obtain an instance of a state element evaluator that can compute the derivatives of this element of the state during propagation.
int	getDimension() Gets the number of parameters (per Order (get)) within this element.
Matrix	getInitialConsiderTransitionMatrix() Gets the optional user-specified initial consider transition matrix.
Matrix	getInitialStateTransitionMatrix() Gets the optional user-specified initial state transition matrix.
DynamicMatrix	getIntegrationDynamicMatrix() Gets a DynamicMatrix which is parameterized on the value of the StateTransitionMatrix during integration.
int	getLinearDimension() Gets the linear dimension of the StateTransitionMatrix.
int	getNumberOfConsiderParameters() Gets the number of consider parameters that have been added to this StateTransitionMatrix.
int	getNumberOfStateParameters() Gets the number of state parameters and derivatives that have been added to this StateTransitionMatrix.
int	getOrder() Gets the order of the differential equation corresponding to this element.
IPartialDifferentiable	getStateDerivative(int index) Gets the state derivative at the specified index which has been added to this StateTransitionMatrix.
int	getStateDimension() Gets the summed dimension of all of the state parameters.
PropagationStateParameter	getStateParameter() Gets a parameter which represents the state during propagation.
IPartialDifferentiable	getStateParameter(int index) Gets the state parameter at the specified index which has been added to this StateTransitionMatrix.
IUpdatePriorToStep	getStateUpdater(EvaluatorGroup group) Creates an object that will update the state of the StateTransitionMatrix in between propagation steps, if necessary.
TransitionType	getTransitionType() Gets whether this StateTransitionMatrix is operating in epoch or piecewise mode.
int	indexOfConsiderParameter(IPartialDifferentiable considerParameter) Searches for the specified considerParameter and returns the index which can be used to access it via StateTransitionMatrix.getConsiderParameter(int) or StateTransitionMatrix.removeConsiderParameterAt(int).
int	indexOfStateDerivative(IPartialDifferentiable stateDerivative) Searches for the specified stateDerivative and returns the index which can be used to access it via StateTransitionMatrix.getStateDerivative(int) or StateTransitionMatrix.removeStateParameterAt(int).
int	indexOfStateParameter(IPartialDifferentiable stateParameter) Searches for the specified stateParameter and returns the index which can be used to access it via StateTransitionMatrix.getStateParameter(int) or StateTransitionMatrix.removeStateParameterAt(int).
static DateMotionCollection1<Matrix>	populateCovarianceCollection(Matrix initialCovariance, DateMotionCollection1<Matrix> stateTransitionMatrices, TransitionType transitionType) Transforms an initial covariance matrix forward in time using the given collection of state transition matrices.
void	removeConsiderParameterAt(int index) Removes the consider parameter at the given index.
void	removeStateParameterAt(int index) Removes the state parameter at the given index, as well as its derivative.
void	setInitialConsiderTransitionMatrix(Matrix value) Sets the optional user-specified initial consider transition matrix.
void	setInitialStateTransitionMatrix(Matrix value) Sets the optional user-specified initial state transition matrix.
void	setStateParameter(PropagationStateParameter value) Sets a parameter which represents the state during propagation.
void	setTransitionType(TransitionType value) Sets whether this StateTransitionMatrix is operating in epoch or piecewise mode.

Methods inherited from class agi.foundation.propagators.advanced.PropagationStateElement

checkForSameDefinition, getIdentification, getIncludeHighestDerivativeInOutput, setIdentification, setIncludeHighestDerivativeInOutput

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StateTransitionMatrix

public StateTransitionMatrix()

Initializes a new instance.

StateTransitionMatrix

protected StateTransitionMatrix(@Nonnull
                                StateTransitionMatrix existingInstance,
                                @Nonnull
                                CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Specified by:

clone in class DefinitionalObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected final boolean checkForSameDefinition(PropagationStateElement other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Specified by:

checkForSameDefinition in class PropagationStateElement

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

checkForSameDefinition

protected boolean checkForSameDefinition(StateTransitionMatrix other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the StateTransitionMatrix.checkForSameDefinition(agi.foundation.propagators.advanced.PropagationStateElement) method.

Overrides:

computeCurrentDefinitionHashCode in class PropagationStateElement

Returns:

The computed hash code.

enumerateDependencies

public void enumerateDependencies(DependencyEnumerator enumerator)

Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon. Derived classes which contain additional dependencies MUST override this method, call the base implementation, and enumerate dependencies introduced by the derived class.

Specified by:

enumerateDependencies in interface IEnumerateDependencies

Overrides:

enumerateDependencies in class DefinitionalObject

Parameters:

enumerator - The enumerator that is informed of the dependencies of this object.

freezeAggregatedObjects

protected void freezeAggregatedObjects()

Called by DefinitionalObject.freeze() to also freeze any objects that are considered to be a part of this object. Derived classes which contain additional aggregated objects MUST override this method, call the base implementation, and freeze aggregated objects introduced by the derived class. The objects that need to be frozen in this method are frequently created in this object's constructor and are not settable via properties.

Overrides:

freezeAggregatedObjects in class DefinitionalObject

addStateParameter

public final void addStateParameter(@Nonnull
                                    IPartialDifferentiable stateParameter,
                                    @Nonnull
                                    IPartialDifferentiable stateDerivative)

Adds a state parameter to the StateTransitionMatrix. The state parameters added here make up the state represented by the state transition matrix. The stateDerivative of the stateParameter is needed in order to calculate the derivative of the state transition matrix so that it can be integrated.

Parameters:

stateParameter - The state parameter to add to those tracked in the StateTransitionMatrix.

stateDerivative - The derivative of the given state parameter.

See Also:

StateTransitionMatrix.getStateParameter(int), StateTransitionMatrix.indexOfStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getStateDerivative(int), StateTransitionMatrix.indexOfStateDerivative(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeStateParameterAt(int), StateTransitionMatrix.getNumberOfStateParameters()

getStateParameter

public final IPartialDifferentiable getStateParameter(int index)

Gets the state parameter at the specified index which has been added to this StateTransitionMatrix.

Parameters:

index - The index of the state parameter to retrieve.

Returns:

A reference to the state parameter at the specified location.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.indexOfStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeStateParameterAt(int), StateTransitionMatrix.getNumberOfStateParameters()

indexOfStateParameter

public final int indexOfStateParameter(IPartialDifferentiable stateParameter)

Searches for the specified stateParameter and returns the index which can be used to access it via StateTransitionMatrix.getStateParameter(int) or StateTransitionMatrix.removeStateParameterAt(int).

Parameters:

stateParameter - The state parameter to search for.

Returns:

The index of the stateParameter if found; otherwise -1.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getStateParameter(int), StateTransitionMatrix.removeStateParameterAt(int), StateTransitionMatrix.getNumberOfStateParameters()

removeStateParameterAt

public final void removeStateParameterAt(int index)

Removes the state parameter at the given index, as well as its derivative.

Parameters:

index - The index of the state parameter and derivative to remove.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getStateParameter(int), StateTransitionMatrix.indexOfStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.indexOfStateDerivative(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getNumberOfStateParameters()

getStateDerivative

public final IPartialDifferentiable getStateDerivative(int index)

Gets the state derivative at the specified index which has been added to this StateTransitionMatrix.

Parameters:

index - The index of the state derivative to retrieve.

Returns:

A reference to the state derivative at the specified location.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.indexOfStateDerivative(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeStateParameterAt(int), StateTransitionMatrix.getNumberOfStateParameters()

indexOfStateDerivative

public final int indexOfStateDerivative(IPartialDifferentiable stateDerivative)

Searches for the specified stateDerivative and returns the index which can be used to access it via StateTransitionMatrix.getStateDerivative(int) or StateTransitionMatrix.removeStateParameterAt(int).

Parameters:

stateDerivative - The state derivative to search for.

Returns:

The index of the stateDerivative if found; otherwise -1.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getStateDerivative(int), StateTransitionMatrix.removeStateParameterAt(int), StateTransitionMatrix.getNumberOfStateParameters()

addConsiderParameter

public final void addConsiderParameter(@Nonnull
                                       IPartialDifferentiable considerParameter)

Adds a consider parameter to the StateTransitionMatrix. Consider parameters can be used when calculating covariance for a state parameter. The transitions are not actually calculated for a consider parameter, however the values of the consider parameter do affect those of the state parameters. For example, if you weren't interested in examining how the uncertainty of the coefficient of drag evolved over time, but were interested in how it's uncertainty affected the uncertainty of the state parameters, then you would add it as a consider parameter.

Parameters:

considerParameter - The consider parameter to add to those tracked in the StateTransitionMatrix.

See Also:

StateTransitionMatrix.getConsiderParameter(int), StateTransitionMatrix.indexOfConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeConsiderParameterAt(int), StateTransitionMatrix.getNumberOfConsiderParameters()

getConsiderParameter

public final IPartialDifferentiable getConsiderParameter(int index)

Gets the consider parameter at the specified index which has been added to this StateTransitionMatrix.

Parameters:

index - The index of the consider parameter to retrieve.

Returns:

A reference to the consider parameter at the specified location.

See Also:

StateTransitionMatrix.addConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.indexOfConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeConsiderParameterAt(int), StateTransitionMatrix.getNumberOfConsiderParameters()

indexOfConsiderParameter

public final int indexOfConsiderParameter(IPartialDifferentiable considerParameter)

Searches for the specified considerParameter and returns the index which can be used to access it via StateTransitionMatrix.getConsiderParameter(int) or StateTransitionMatrix.removeConsiderParameterAt(int).

Parameters:

considerParameter - The consider parameter to search for.

Returns:

The index of the considerParameter if found; otherwise -1.

See Also:

StateTransitionMatrix.addConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getConsiderParameter(int), StateTransitionMatrix.removeConsiderParameterAt(int), StateTransitionMatrix.getNumberOfConsiderParameters()

removeConsiderParameterAt

public final void removeConsiderParameterAt(int index)

Removes the consider parameter at the given index.

Parameters:

index - The index of the consider parameter to be removed.

See Also:

StateTransitionMatrix.addConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getConsiderParameter(int), StateTransitionMatrix.indexOfConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getNumberOfConsiderParameters()

getOrder

public int getOrder()

Gets the order of the differential equation corresponding to this element.

Specified by:

getOrder in class PropagationStateElement

getDimension

public int getDimension()

Gets the number of parameters (per Order (get)) within this element.

Specified by:

getDimension in class PropagationStateElement

getLinearDimension

public final int getLinearDimension()

Gets the linear dimension of the StateTransitionMatrix.

The StateTransitionMatrix takes the form of a square matrix of dimensions L x L, where L is equal to N, the total dimension of the state parameters (StateDimension (get / set)) plus Q, the total dimension of the consider parameters (ConsiderDimension (get / set)). The StateTransitionMatrix's dimension as far as the propagation state is concerned is L squared, and that is what the Dimension (get) property returns. This property returns the value of L.

getStateDimension

public final int getStateDimension()

Gets the summed dimension of all of the state parameters.

getNumberOfStateParameters

public final int getNumberOfStateParameters()

Gets the number of state parameters and derivatives that have been added to this StateTransitionMatrix.

See Also:

StateTransitionMatrix.addStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable, agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getStateParameter(int), StateTransitionMatrix.getStateDerivative(int), StateTransitionMatrix.indexOfStateParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.indexOfStateDerivative(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeStateParameterAt(int)

getConsiderDimension

public final int getConsiderDimension()

Gets the summed dimension of all of the consider parameters.

getNumberOfConsiderParameters

public final int getNumberOfConsiderParameters()

Gets the number of consider parameters that have been added to this StateTransitionMatrix.

See Also:

StateTransitionMatrix.addConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.getConsiderParameter(int), StateTransitionMatrix.indexOfConsiderParameter(agi.foundation.numericalmethods.advanced.IPartialDifferentiable), StateTransitionMatrix.removeConsiderParameterAt(int)

getTransitionType

@Nonnull
public final TransitionType getTransitionType()

Gets whether this StateTransitionMatrix is operating in epoch or piecewise mode. By default, this is set to TransitionType.EPOCH_TRANSITION, which means that the state transition matrix at each time step transforms the state from the epoch state to the state at that time step.

setTransitionType

public final void setTransitionType(@Nonnull
                                    TransitionType value)

Sets whether this StateTransitionMatrix is operating in epoch or piecewise mode. By default, this is set to TransitionType.EPOCH_TRANSITION, which means that the state transition matrix at each time step transforms the state from the epoch state to the state at that time step.

getStateParameter

public PropagationStateParameter getStateParameter()

Gets a parameter which represents the state during propagation. In general, users should never need to explicitly set this property. It should only be set when multiple NumericalPropagator objects are running in the same EvaluatorGroup, such as when elements of a state require additional instances of a NumericalPropagator inside their implementation in order to produce their values. In such cases, it may be necessary to distinguish between the state of the exterior propagator and the state of the interior propagator. In these cases, it is up to the user to ensure that both the state and all of its elements are configured with the same parameter. Otherwise, the state will throw an exception when creating its propagator.

Specified by:

getStateParameter in class PropagationStateElement

setStateParameter

public void setStateParameter(PropagationStateParameter value)

Sets a parameter which represents the state during propagation. In general, users should never need to explicitly set this property. It should only be set when multiple NumericalPropagator objects are running in the same EvaluatorGroup, such as when elements of a state require additional instances of a NumericalPropagator inside their implementation in order to produce their values. In such cases, it may be necessary to distinguish between the state of the exterior propagator and the state of the interior propagator. In these cases, it is up to the user to ensure that both the state and all of its elements are configured with the same parameter. Otherwise, the state will throw an exception when creating its propagator.

Specified by:

setStateParameter in class PropagationStateElement

getIntegrationDynamicMatrix

public final DynamicMatrix getIntegrationDynamicMatrix()

Gets a DynamicMatrix which is parameterized on the value of the StateTransitionMatrix during integration. This matrix is only valid while the NumericalPropagator is running.

getInitialStateTransitionMatrix

public final Matrix getInitialStateTransitionMatrix()

Gets the optional user-specified initial state transition matrix. In general this should be left null and the default value will be used instead. The default initial state takes the form of a StateDimension (get / set) by StateDimension (get / set) identity matrix.

setInitialStateTransitionMatrix

public final void setInitialStateTransitionMatrix(Matrix value)

Sets the optional user-specified initial state transition matrix. In general this should be left null and the default value will be used instead. The default initial state takes the form of a StateDimension (get / set) by StateDimension (get / set) identity matrix.

getInitialConsiderTransitionMatrix

public final Matrix getInitialConsiderTransitionMatrix()

Gets the optional user-specified initial consider transition matrix. In general this should be left null and the default value will be used instead. The default initial state takes the form of a StateDimension (get / set) by ConsiderDimension (get / set) zero matrix.

setInitialConsiderTransitionMatrix

public final void setInitialConsiderTransitionMatrix(Matrix value)

Sets the optional user-specified initial consider transition matrix. In general this should be left null and the default value will be used instead. The default initial state takes the form of a StateDimension (get / set) by ConsiderDimension (get / set) zero matrix.

populateCovarianceCollection

@Nonnull
public static DateMotionCollection1<Matrix> populateCovarianceCollection(@Nonnull
                                                                                   Matrix initialCovariance,
                                                                                   @Nonnull
                                                                                   DateMotionCollection1<Matrix> stateTransitionMatrices,
                                                                                   @Nonnull
                                                                                   TransitionType transitionType)

Transforms an initial covariance matrix forward in time using the given collection of state transition matrices.

Parameters:

initialCovariance - The initial covariance matrix that corresponds with the first time step in the collection.

stateTransitionMatrices - The DateMotionCollection1 of the state transition matrices and their corresponding times to be used to move the covariance values forward in time.

transitionType - Indicates type of the given state transition matrices. See also TransitionType (get / set).

Returns:

A new date motion collection of covariances which corresponds to the state transition matrices.

getConverter

public PropagationStateElementConverter getConverter(EvaluatorGroup group,
                                                     @Nonnull
                                                     Motion1<int[]> stateInputIndices)

Gets an instance of an output type which can convert the output of propagation back into the native type of this state element. This method is also responsible for configuring the state parameter and the state input indices on any parameterized geometry types used by this element. Each parameterized geometry type will have a static configuration method which will allow it to configure itself in a particular EvaluatorGroup.

Specified by:

getConverter in class PropagationStateElement

Parameters:

group - The evaluator group in which to configure the parameters.

stateInputIndices - The set of indices corresponding to the location of each value or derivative of this state element in the overall state.

Returns:

The output instance associated with this state element.

getStateUpdater

public IUpdatePriorToStep getStateUpdater(EvaluatorGroup group)

Creates an object that will update the state of the StateTransitionMatrix in between propagation steps, if necessary.

If TransitionType (get / set) is PiecewiseTransition then the matrices produced during propagation represent the transition matrices from the previous time step to their own time step. This means that at the beginning of each propagation step the value of the state transition matrix must be reset to the identity matrix.

If TransitionType (get / set) is EpochTransition then the matrices produced during propagation represent the transition matrices from the epoch to their own time step, and this reset is not necessary.

Overrides:

getStateUpdater in class PropagationStateElement

Parameters:

group - The EvaluatorGroup the state updater will be part of.

Returns:

null if TransitionType (get / set) is TransitionType.EpochTransition, otherwise an IUpdatePriorToStep to reset the matrix to Identity at the beginning of each propagation step.

Throws:

ArgumentNullException - Thrown when group is null.

getDerivatives

public PropagationStateElementEvaluator getDerivatives(EvaluatorGroup group)

This is used by the NumericalPropagatorDefinition to obtain an instance of a state element evaluator that can compute the derivatives of this element of the state during propagation. It cannot be used outside of a NumericalPropagator as the geometry for the propagation state will be unavailable.

Specified by:

getDerivatives in class PropagationStateElement

Parameters:

group - The group in which to create the evaluator and its dependents.

Returns:

The evaluator that can compute the derivatives of this element of the state.