Runge-Kutta-Nystroem stepper based on Eigen implementation for the following ODE: More...

#include <Acts/Propagator/EigenStepper.hpp>

Collaboration diagram for Acts::EigenStepper< extension_t >:

Classes
struct	Config
struct	Options
struct	State
	State for track parameter propagation. More...

Public Types
using	BoundState = std::tuple<BoundTrackParameters, Jacobian, double>
	Type alias for bound state tuple containing parameters, jacobian, and path length.
using	Covariance = BoundSquareMatrix
	Type alias for covariance matrix (bound square matrix).
using	Jacobian = BoundMatrix
	Jacobian, Covariance and State definitions.

Public Member Functions
	EigenStepper (const Config &config)
	Constructor with configuration.
	EigenStepper (std::shared_ptr< const MagneticFieldProvider > bField)
	Constructor requires knowledge of the detector's magnetic field.
double	absoluteMomentum (const State &state) const
	Absolute momentum accessor.
Result< BoundState >	boundState (State &state, const Surface &surface, bool transportCov=true, const FreeToBoundCorrection &freeToBoundCorrection=FreeToBoundCorrection(false)) const
	Create and return the bound state at the current position.
double	charge (const State &state) const
	Charge access.
BoundState	curvilinearState (State &state, bool transportCov=true) const
	Create and return a curvilinear state at the current position.
Vector3	direction (const State &state) const
	Momentum direction accessor.
Result< Vector3 >	getField (State &state, const Vector3 &pos) const
	Get the field for the stepping, it checks first if the access is still within the Cell, and updates the cell if necessary.
double	getStepSize (const State &state, ConstrainedStep::Type stype) const
	Get the step size.
void	initialize (State &state, const BoundTrackParameters &par) const
	Initialize the stepper state from bound track parameters.
void	initialize (State &state, const BoundVector &boundParams, const std::optional< BoundMatrix > &cov, ParticleHypothesis particleHypothesis, const Surface &surface) const
	Initialize the stepper state from bound parameters and surface.
State	makeState (const Options &options) const
	Create a stepper state from given options.
Vector3	momentum (const State &state) const
	Momentum accessor.
std::string	outputStepSize (const State &state) const
	Output the Step Size - single component.
const ParticleHypothesis &	particleHypothesis (const State &state) const
	Particle hypothesis.
Vector3	position (const State &state) const
	Global particle position accessor.
bool	prepareCurvilinearState (State &state) const
	If necessary fill additional members needed for curvilinearState.
double	qOverP (const State &state) const
	QoP direction accessor.
void	releaseStepSize (State &state, ConstrainedStep::Type stype) const
	Release the Step size.
void	setIdentityJacobian (State &state) const
	Method that reset the Jacobian to the Identity for when no bound state are available.
Result< double >	step (State &state, Direction propDir, const IVolumeMaterial *material) const
	Perform a Runge-Kutta track parameter propagation step.
double	time (const State &state) const
	Time access.
void	transportCovarianceToBound (State &state, const Surface &surface, const FreeToBoundCorrection &freeToBoundCorrection=FreeToBoundCorrection(false)) const
	Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state.
void	transportCovarianceToCurvilinear (State &state) const
	Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state.
void	update (State &state, const FreeVector &freeParams, const BoundVector &boundParams, const Covariance &covariance, const Surface &surface) const
	Method to update a stepper state to the some parameters.
void	update (State &state, const Vector3 &uposition, const Vector3 &udirection, double qOverP, double time) const
	Method to update the stepper state.
void	updateStepSize (State &state, const NavigationTarget &target, Direction direction, ConstrainedStep::Type stype) const
	Update step size.
void	updateStepSize (State &state, double stepSize, ConstrainedStep::Type stype) const
	Update step size - explicitly with a double.
IntersectionStatus	updateSurfaceStatus (State &state, const Surface &surface, std::uint8_t index, Direction propDir, const BoundaryTolerance &boundaryTolerance, double surfaceTolerance, ConstrainedStep::Type stype, const Logger &logger=getDummyLogger()) const
	Update surface status.

Protected Attributes
std::shared_ptr< const MagneticFieldProvider >	m_bField
	Magnetic field inside of the detector.

Detailed Description

template<typename extension_t = EigenStepperDefaultExtension>
class Acts::EigenStepper< extension_t >

Runge-Kutta-Nystroem stepper based on Eigen implementation for the following ODE:

r = (x,y,z) ... global position T = (Ax,Ay,Az) ... momentum direction (normalized)

dr/ds = T dT/ds = q/p * (T x B)

with s being the arc length of the track, q the charge of the particle, p the momentum magnitude and B the magnetic field

Member Typedef Documentation

◆ BoundState

template<typename extension_t = EigenStepperDefaultExtension>

using Acts::EigenStepper< extension_t >::BoundState = std::tuple<BoundTrackParameters, Jacobian, double>

Type alias for bound state tuple containing parameters, jacobian, and path length.

◆ Covariance

template<typename extension_t = EigenStepperDefaultExtension>

using Acts::EigenStepper< extension_t >::Covariance = BoundSquareMatrix

Type alias for covariance matrix (bound square matrix).

◆ Jacobian

template<typename extension_t = EigenStepperDefaultExtension>

using Acts::EigenStepper< extension_t >::Jacobian = BoundMatrix

Jacobian, Covariance and State definitions.

Constructor & Destructor Documentation

◆ EigenStepper() [1/2]

template<typename extension_t = EigenStepperDefaultExtension>

Acts::EigenStepper< extension_t >::EigenStepper ( std::shared_ptr< const MagneticFieldProvider > bField )

explicit

Constructor requires knowledge of the detector's magnetic field.

Parameters

bField The magnetic field provider

◆ EigenStepper() [2/2]

template<typename extension_t = EigenStepperDefaultExtension>

Acts::EigenStepper< extension_t >::EigenStepper ( const Config & config )

explicit

Constructor with configuration.

Parameters

[in] config The configuration of the stepper

Member Function Documentation

◆ absoluteMomentum()

template<typename extension_t = EigenStepperDefaultExtension>

double Acts::EigenStepper< extension_t >::absoluteMomentum ( const State & state ) const

Absolute momentum accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Absolute momentum magnitude

◆ boundState()

template<typename extension_t = EigenStepperDefaultExtension>

Result< BoundState > Acts::EigenStepper< extension_t >::boundState	(	State &	state,
		const Surface &	surface,
		bool	transportCov = true,
		const FreeToBoundCorrection &	freeToBoundCorrection = FreeToBoundCorrection(false) ) const

Create and return the bound state at the current position.

This transports (if necessary) the covariance to the surface and creates a bound state. It does not check if the transported state is at the surface, this needs to be guaranteed by the propagator

Parameters

[in]	state	State that will be presented as `BoundState`
[in]	surface	The surface to which we bind the state
[in]	transportCov	Flag steering covariance transport
[in]	freeToBoundCorrection	Correction for non-linearity effect during transform from free to bound

Returns

A bound state:

the parameters at the surface
the stepwise jacobian towards it (from last bound)
and the path length (from start - for ordering)

◆ charge()

template<typename extension_t = EigenStepperDefaultExtension>

double Acts::EigenStepper< extension_t >::charge ( const State & state ) const

Charge access.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Electric charge of the particle

◆ curvilinearState()

template<typename extension_t = EigenStepperDefaultExtension>

BoundState Acts::EigenStepper< extension_t >::curvilinearState	(	State &	state,
		bool	transportCov = true ) const

Create and return a curvilinear state at the current position.

This transports (if necessary) the covariance to the current position and creates a curvilinear state.

Parameters

[in]	state	State that will be presented as `CurvilinearState`
[in]	transportCov	Flag steering covariance transport

Returns

A curvilinear state:

the curvilinear parameters at given position
the stepweise jacobian towards it (from last bound)
and the path length (from start - for ordering)

◆ direction()

template<typename extension_t = EigenStepperDefaultExtension>

Vector3 Acts::EigenStepper< extension_t >::direction ( const State & state ) const

Momentum direction accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current normalized direction vector

◆ getField()

template<typename extension_t = EigenStepperDefaultExtension>

Result< Vector3 > Acts::EigenStepper< extension_t >::getField	(	State &	state,
		const Vector3 &	pos ) const

Get the field for the stepping, it checks first if the access is still within the Cell, and updates the cell if necessary.

Parameters

[in,out]	state	is the propagation state associated with the track the magnetic field cell is used (and potentially updated)
[in]	pos	is the field position

Returns: Magnetic field vector at the given position or error

◆ getStepSize()

template<typename extension_t = EigenStepperDefaultExtension>

double Acts::EigenStepper< extension_t >::getStepSize	(	const State &	state,
		ConstrainedStep::Type	stype ) const

Get the step size.

Parameters

state	[in] The stepping state (thread-local cache)
stype	[in] The step size type to be returned

Returns: Current step size for the specified constraint type

◆ initialize() [1/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::initialize	(	State &	state,
		const BoundTrackParameters &	par ) const

Initialize the stepper state from bound track parameters.

Parameters

state	Stepper state to initialize
par	Bound track parameters to initialize from

◆ initialize() [2/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::initialize	(	State &	state,
		const BoundVector &	boundParams,
		const std::optional< BoundMatrix > &	cov,
		ParticleHypothesis	particleHypothesis,
		const Surface &	surface ) const

Initialize the stepper state from bound parameters and surface.

Parameters

state	Stepper state to initialize
boundParams	Vector of bound track parameters
cov	Optional covariance matrix
particleHypothesis	Particle hypothesis for the track
surface	Surface associated with the parameters

◆ makeState()

template<typename extension_t = EigenStepperDefaultExtension>

State Acts::EigenStepper< extension_t >::makeState ( const Options & options ) const

Create a stepper state from given options.

Parameters

options Configuration options for the stepper state

Returns: Initialized stepper state object

◆ momentum()

template<typename extension_t = EigenStepperDefaultExtension>

Vector3 Acts::EigenStepper< extension_t >::momentum ( const State & state ) const

Momentum accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current momentum vector

◆ outputStepSize()

template<typename extension_t = EigenStepperDefaultExtension>

std::string Acts::EigenStepper< extension_t >::outputStepSize ( const State & state ) const

Output the Step Size - single component.

Parameters

state [in,out] The stepping state (thread-local cache)

Returns: String representation of the current step size

◆ particleHypothesis()

template<typename extension_t = EigenStepperDefaultExtension>

const ParticleHypothesis & Acts::EigenStepper< extension_t >::particleHypothesis ( const State & state ) const

Particle hypothesis.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Reference to the particle hypothesis used

◆ position()

template<typename extension_t = EigenStepperDefaultExtension>

Vector3 Acts::EigenStepper< extension_t >::position ( const State & state ) const

Global particle position accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current global position vector

◆ prepareCurvilinearState()

template<typename extension_t = EigenStepperDefaultExtension>

bool Acts::EigenStepper< extension_t >::prepareCurvilinearState ( State & state ) const

If necessary fill additional members needed for curvilinearState.

Compute path length derivatives in case they have not been computed yet, which is the case if no step has been executed yet.

Parameters

[in,out] state The state of the stepper

Returns: true if nothing is missing after this call, false otherwise.

◆ qOverP()

template<typename extension_t = EigenStepperDefaultExtension>

double Acts::EigenStepper< extension_t >::qOverP ( const State & state ) const

QoP direction accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Charge over momentum (q/p) value

◆ releaseStepSize()

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::releaseStepSize	(	State &	state,
		ConstrainedStep::Type	stype ) const

Release the Step size.

Parameters

	state	[in,out] The stepping state (thread-local cache)
[in]	stype	The step size type to be released

◆ setIdentityJacobian()

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::setIdentityJacobian ( State & state ) const

Method that reset the Jacobian to the Identity for when no bound state are available.

Parameters

[in,out] state State of the stepper

◆ step()

template<typename extension_t = EigenStepperDefaultExtension>

Result< double > Acts::EigenStepper< extension_t >::step	(	State &	state,
		Direction	propDir,
		const IVolumeMaterial *	material ) const

Perform a Runge-Kutta track parameter propagation step.

Parameters

[in,out]	state	State of the stepper
	propDir	is the direction of propagation
	material	is the optional volume material we are stepping through.

Returns: the result of the step

Note: The state contains the desired step size. It can be negative during backwards track propagation, and since we're using an adaptive algorithm, it can be modified by the stepper class during propagation.

◆ time()

template<typename extension_t = EigenStepperDefaultExtension>

double Acts::EigenStepper< extension_t >::time ( const State & state ) const

Time access.

Parameters

state [in] The stepping state (thread-local cache)

Returns: The time coordinate from the free parameters vector

◆ transportCovarianceToBound()

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::transportCovarianceToBound	(	State &	state,
		const Surface &	surface,
		const FreeToBoundCorrection &	freeToBoundCorrection = FreeToBoundCorrection(false) ) const

Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state.

Template Parameters

surface_t the Surface type

Parameters

[in,out]	state	State of the stepper
[in]	surface	is the surface to which the covariance is forwarded to
[in]	freeToBoundCorrection	Correction for non-linearity effect during transform from free to bound

Note: no check is done if the position is actually on the surface

◆ transportCovarianceToCurvilinear()

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::transportCovarianceToCurvilinear ( State & state ) const

Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state.

Parameters

[in,out] state State of the stepper

◆ update() [1/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::update	(	State &	state,
		const FreeVector &	freeParams,
		const BoundVector &	boundParams,
		const Covariance &	covariance,
		const Surface &	surface ) const

Method to update a stepper state to the some parameters.

Parameters

[in,out]	state	State object that will be updated
[in]	freeParams	Free parameters that will be written into `state`
[in]	boundParams	Corresponding bound parameters used to update jacToGlobal in `state`
[in]	covariance	The covariance that will be written into `state`
[in]	surface	The surface used to update the jacToGlobal

◆ update() [2/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::update	(	State &	state,
		const Vector3 &	uposition,
		const Vector3 &	udirection,
		double	qOverP,
		double	time ) const

Method to update the stepper state.

Parameters

[in,out]	state	State object that will be updated
[in]	uposition	the updated position
[in]	udirection	the updated direction
[in]	qOverP	the updated qOverP value
[in]	time	the updated time value

◆ updateStepSize() [1/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::updateStepSize	(	State &	state,
		const NavigationTarget &	target,
		Direction	direction,
		ConstrainedStep::Type	stype ) const

Update step size.

This method intersects the provided surface and update the navigation step estimation accordingly (hence it changes the state). It also returns the status of the intersection to trigger onSurface in case the surface is reached.

Parameters

state	[in,out] The stepping state (thread-local cache)
target	[in] The NavigationTarget
direction	[in] The propagation direction
stype	[in] The step size type to be set

◆ updateStepSize() [2/2]

template<typename extension_t = EigenStepperDefaultExtension>

void Acts::EigenStepper< extension_t >::updateStepSize	(	State &	state,
		double	stepSize,
		ConstrainedStep::Type	stype ) const

Update step size - explicitly with a double.

Parameters

state	[in,out] The stepping state (thread-local cache)
stepSize	[in] The step size value
stype	[in] The step size type to be set

◆ updateSurfaceStatus()

template<typename extension_t = EigenStepperDefaultExtension>

IntersectionStatus Acts::EigenStepper< extension_t >::updateSurfaceStatus	(	State &	state,
		const Surface &	surface,
		std::uint8_t	index,
		Direction	propDir,
		const BoundaryTolerance &	boundaryTolerance,
		double	surfaceTolerance,
		ConstrainedStep::Type	stype,
		const Logger &	logger = getDummyLogger() ) const

Update surface status.

It checks the status to the reference surface & updates the step size accordingly

Parameters

[in,out]	state	The stepping state (thread-local cache)
[in]	surface	The surface provided
[in]	index	The surface intersection index
[in]	propDir	The propagation direction
[in]	boundaryTolerance	The boundary check for this status update
[in]	surfaceTolerance	Surface tolerance used for intersection
[in]	stype	The step size type to be set
[in]	logger	A `Logger` instance

Returns: Status of the intersection indicating whether surface was reached

Member Data Documentation

◆ m_bField

template<typename extension_t = EigenStepperDefaultExtension>

std::shared_ptr<const MagneticFieldProvider> Acts::EigenStepper< extension_t >::m_bField

protected

Magnetic field inside of the detector.

Classes

Public Types

Public Member Functions

Protected Attributes

Detailed Description

Member Typedef Documentation

◆ BoundState

◆ Covariance

◆ Jacobian

Constructor & Destructor Documentation

◆ EigenStepper() [1/2]

◆ EigenStepper() [2/2]

Member Function Documentation

◆ absoluteMomentum()

◆ boundState()

◆ charge()

◆ curvilinearState()

◆ direction()

◆ getField()

◆ getStepSize()

◆ initialize() [1/2]

◆ initialize() [2/2]

◆ makeState()

◆ momentum()

◆ outputStepSize()

◆ particleHypothesis()

◆ position()

◆ prepareCurvilinearState()

◆ qOverP()

◆ releaseStepSize()

◆ setIdentityJacobian()

◆ step()

◆ time()

◆ transportCovarianceToBound()

◆ transportCovarianceToCurvilinear()

◆ update() [1/2]

◆ update() [2/2]

◆ updateStepSize() [1/2]

◆ updateStepSize() [2/2]

◆ updateSurfaceStatus()

Member Data Documentation

◆ m_bField