Class to model tracks as 2D density functions based on their d0 and z0 perigee parameters (mean value) and covariance matrices (determining the width of the function) More...

#include <acts/blob/sPHENIX/Core/include/Acts/Vertexing/GaussianTrackDensity.hpp>

Collaboration diagram for Acts::GaussianTrackDensity< input_track_t >:

Classes
struct	Config
	The Config struct. More...

class	GaussianTrackDensityStore

struct	State
	The State struct. More...

struct	TrackEntry
	Struct to store information for a single track. More...

Public Member Functions
	GaussianTrackDensity ()=default
	Default constructor.

	GaussianTrackDensity (const Config &cfg)
	Constructor with config.

std::pair< double, double >	globalMaximumWithWidth (State &state, const std::vector< const input_track_t * > &trackList, const std::function< BoundTrackParameters(input_track_t)> &extractParameters) const
	Calculates z position of global maximum with Gaussian width for density function. Strategy: The global maximum must be somewhere near a track. Since we can calculate the first and second derivatives, at each point we can determine a) whether the function is curved up (minimum) or down (maximum) b) the distance to nearest maximum, assuming either Newton (parabolic) or Gaussian local behavior. For each track where the second derivative is negative, find step to nearest maximum, take that step and then do one final refinement. The largest density encountered in this procedure (after checking all tracks) is considered the maximum.

double	globalMaximum (State &state, const std::vector< const input_track_t * > &trackList, const std::function< BoundTrackParameters(input_track_t)> &extractParameters) const
	Calculates the z position of the global maximum.

Private Member Functions
Result< void >	addTracks (State &state, const std::vector< const input_track_t * > &trackList, const std::function< BoundTrackParameters(input_track_t)> &extractParameters) const
	Add a track to the set being considered.

std::tuple< double, double, double >	trackDensityAndDerivatives (State &state, double z) const
	Evaluate the density function and its two first derivatives at the specified coordinate along the beamline.

std::tuple< double, double, double >	updateMaximum (double newZ, double newValue, double newSecondDerivative, double maxZ, double maxValue, double maxSecondDerivative) const
	Update the current maximum values.

double	stepSize (double y, double dy, double ddy) const
	Calculates the step size.

Private Attributes
Config	m_cfg
	The configuration.

Detailed Description

template<typename input_track_t>
class Acts::GaussianTrackDensity< input_track_t >

Class to model tracks as 2D density functions based on their d0 and z0 perigee parameters (mean value) and covariance matrices (determining the width of the function)

Definition at line 24 of file GaussianTrackDensity.hpp.

View newest version in sPHENIX GitHub at line 24 of file GaussianTrackDensity.hpp

Constructor & Destructor Documentation

template<typename input_track_t >

Acts::GaussianTrackDensity< input_track_t >::GaussianTrackDensity ( )

default

Default constructor.

template<typename input_track_t >

Acts::GaussianTrackDensity< input_track_t >::GaussianTrackDensity ( const Config & cfg )

inline

Constructor with config.

Definition at line 93 of file GaussianTrackDensity.hpp.

View newest version in sPHENIX GitHub at line 93 of file GaussianTrackDensity.hpp

Member Function Documentation

template<typename input_track_t >

Result< void > Acts::GaussianTrackDensity< input_track_t >::addTracks	(	State &	state,
		const std::vector< const input_track_t * > &	trackList,
		const std::function< BoundTrackParameters(input_track_t)> &	extractParameters
	)		const

private

Add a track to the set being considered.

Parameters

state	The track density state
trackList	All input tracks
extractParameters	Function extracting BoundTrackParameters from InputTrack

Definition at line 78 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 78 of file GaussianTrackDensity.ipp

References Acts::GenericBoundTrackParameters< particle_hypothesis_t >::covariance(), Acts::eBoundLoc0, Acts::eBoundLoc1, m_cfg(), Acts::GenericBoundTrackParameters< particle_hypothesis_t >::parameters(), and Acts::GaussianTrackDensity< input_track_t >::State::trackEntries.

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template<typename input_track_t >

double Acts::GaussianTrackDensity< input_track_t >::globalMaximum	(	State &	state,
		const std::vector< const input_track_t * > &	trackList,
		const std::function< BoundTrackParameters(input_track_t)> &	extractParameters
	)		const

Calculates the z position of the global maximum.

Parameters

state	The track density state
trackList	All input tracks
extractParameters	Function extracting BoundTrackParameters from InputTrack

Returns: z position of the global maximum

Definition at line 70 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 70 of file GaussianTrackDensity.ipp

template<typename input_track_t >

std::pair< double, double > Acts::GaussianTrackDensity< input_track_t >::globalMaximumWithWidth	(	State &	state,
		const std::vector< const input_track_t * > &	trackList,
		const std::function< BoundTrackParameters(input_track_t)> &	extractParameters
	)		const

Calculates z position of global maximum with Gaussian width for density function. Strategy: The global maximum must be somewhere near a track. Since we can calculate the first and second derivatives, at each point we can determine a) whether the function is curved up (minimum) or down (maximum) b) the distance to nearest maximum, assuming either Newton (parabolic) or Gaussian local behavior. For each track where the second derivative is negative, find step to nearest maximum, take that step and then do one final refinement. The largest density encountered in this procedure (after checking all tracks) is considered the maximum.

Parameters

state	The track density state
trackList	All input tracks
extractParameters	Function extracting BoundTrackParameters from InputTrack

Returns: Pair of position of global maximum and Gaussian width

Definition at line 17 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 17 of file GaussianTrackDensity.ipp

References Acts::Test::stepSize, and Acts::GaussianTrackDensity< input_track_t >::State::trackEntries.

template<typename input_track_t >

double Acts::GaussianTrackDensity< input_track_t >::stepSize	(	double	y,
		double	dy,
		double	ddy
	)		const

private

Calculates the step size.

Parameters

y	Position value
dy	First derivative
ddy	Second derivative

Returns: The step size

Definition at line 158 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 158 of file GaussianTrackDensity.ipp

References m_cfg().

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template<typename input_track_t >

std::tuple< double, double, double > Acts::GaussianTrackDensity< input_track_t >::trackDensityAndDerivatives	(	State &	state,
		double	z
	)		const

private

Evaluate the density function and its two first derivatives at the specified coordinate along the beamline.

Parameters

state	The track density state
z	z-position along the beamline

Returns: Track density, first and second derivatives

Definition at line 135 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 135 of file GaussianTrackDensity.ipp

References Acts::GaussianTrackDensity< input_track_t >::GaussianTrackDensityStore::addTrackToDensity(), Acts::GaussianTrackDensity< input_track_t >::GaussianTrackDensityStore::densityAndDerivatives(), and Acts::GaussianTrackDensity< input_track_t >::State::trackEntries.

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template<typename input_track_t >

std::tuple< double, double, double > Acts::GaussianTrackDensity< input_track_t >::updateMaximum	(	double	newZ,
		double	newValue,
		double	newSecondDerivative,
		double	maxZ,
		double	maxValue,
		double	maxSecondDerivative
	)		const

private

Update the current maximum values.

Parameters

newZ	The new z value
newValue	The new value at z position
newSecondDerivative	The new second derivative
maxZ	Maximum z value, will be compared against `newZ`
maxValue	Maximum value
maxSecondDerivative	Maximum of the second derivative

Returns: The max z position, the max value at z position, the max second derivative

Definition at line 146 of file GaussianTrackDensity.ipp.

View newest version in sPHENIX GitHub at line 146 of file GaussianTrackDensity.ipp

References maxZ.

Member Data Documentation

template<typename input_track_t >

Config Acts::GaussianTrackDensity< input_track_t >::m_cfg

private

The configuration.

Definition at line 134 of file GaussianTrackDensity.hpp.

View newest version in sPHENIX GitHub at line 134 of file GaussianTrackDensity.hpp

The documentation for this class was generated from the following files:

acts/blob/sPHENIX/Core/include/Acts/Vertexing/GaussianTrackDensity.hpp
acts/blob/sPHENIX/Core/include/Acts/Vertexing/GaussianTrackDensity.ipp

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

template<typename input_track_t> class Acts::GaussianTrackDensity< input_track_t >

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

template<typename input_track_t>
class Acts::GaussianTrackDensity< input_track_t >