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/master/Core/include/Acts/Vertexing/TrackDensity.hpp>

Collaboration diagram for Acts::TrackDensity:

Classes
struct	Config
	The Config struct. More...

struct	State
	The State struct. More...

class	TrackDensityStore

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

Public Member Functions
	TrackDensity ()=default
	Default constructor.

	TrackDensity (const Config &cfg)
	Constructor with config.

void	addTrack (State &state, const BoundParameters &trk, double d0SignificanceCut, double z0SignificanceCut) const
	Add a track to the set being considered.

std::pair< double, double >	globalMaximumWithWidth (State &state) 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
	Calculates the z position of the global maximum.

double	trackDensity (State &state, double z) const
	Evaluate the density function at the specified coordinate along the beamline.

double	trackDensity (State &state, double z, double &firstDerivative, double &secondDerivative) const
	Evaluate the density function and its two first derivatives at the specified coordinate along the beamline.

Private Member Functions
void	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

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 22 of file TrackDensity.hpp.

View newest version in sPHENIX GitHub at line 22 of file TrackDensity.hpp

Constructor & Destructor Documentation

Acts::TrackDensity::TrackDensity ( )

default

Default constructor.

Acts::TrackDensity::TrackDensity ( const Config & cfg )

inline

Constructor with config.

Definition at line 71 of file TrackDensity.hpp.

View newest version in sPHENIX GitHub at line 71 of file TrackDensity.hpp

Member Function Documentation

void Acts::TrackDensity::addTrack	(	State &	state,
		const BoundParameters &	trk,
		double	d0SignificanceCut,
		double	z0SignificanceCut
	)		const

Add a track to the set being considered.

Parameters

state	The track density state
trk	Track parameters.
d0SignificanceCut	Significance cut on d0.
z0SignificanceCut	Significance cut on z0.

Definition at line 12 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 12 of file TrackDensity.cpp

References Acts::SingleTrackParameters< ChargePolicy >::covariance(), Acts::eLOC_D0, Acts::eLOC_Z0, M_PI, Acts::SingleTrackParameters< ChargePolicy >::parameters(), Acts::TrackDensity::State::trackEntries, and G4InuclParticleNames::z0.

Referenced by Acts::GaussianTrackDensity::addTracks().

Here is the call graph for this function:

Here is the caller graph for this function:

double Acts::TrackDensity::globalMaximum ( State & state ) const

Calculates the z position of the global maximum.

Parameters

state The track density state

Returns: z position of the global maximum

Definition at line 92 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 92 of file TrackDensity.cpp

Referenced by Acts::GaussianTrackDensity::globalMaximum().

Here is the caller graph for this function:

std::pair< double, double > Acts::TrackDensity::globalMaximumWithWidth ( State & state ) 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

Returns: Pair of position of global maximum and Gaussian width

Definition at line 55 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 55 of file TrackDensity.cpp

References track, and Acts::TrackDensity::State::trackEntries.

Referenced by Acts::GaussianTrackDensity::globalMaximumWithWidth().

Here is the caller graph for this function:

double Acts::TrackDensity::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 126 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 126 of file TrackDensity.cpp

double Acts::TrackDensity::trackDensity	(	State &	state,
		double	z
	)		const

Evaluate the density function at the specified coordinate along the beamline.

Parameters

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

Returns: The track density value

Definition at line 96 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 96 of file TrackDensity.cpp

double Acts::TrackDensity::trackDensity	(	State &	state,
		double	z,
		double &	firstDerivative,
		double &	secondDerivative
	)		const

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
[out]	firstDerivative	The first derivative
[out]	secondDerivative	The second derivative

Returns: The track density value

Definition at line 102 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 102 of file TrackDensity.cpp

References Acts::TrackDensity::TrackDensityStore::addTrackToDensity(), Acts::TrackDensity::TrackDensityStore::density(), Acts::TrackDensity::TrackDensityStore::firstDerivative(), Acts::TrackDensity::TrackDensityStore::secondDerivative(), and Acts::TrackDensity::State::trackEntries.

Here is the call graph for this function:

void Acts::TrackDensity::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
[out]	maxZ	The max z value
[out]	maxValue	The max value at z position
[out]	maxSecondDerivative	The max second derivative

Definition at line 115 of file TrackDensity.cpp.

View newest version in sPHENIX GitHub at line 115 of file TrackDensity.cpp

Member Data Documentation

Config Acts::TrackDensity::m_cfg

private

The configuration.

Definition at line 152 of file TrackDensity.hpp.

View newest version in sPHENIX GitHub at line 152 of file TrackDensity.hpp

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

acts/blob/master/Core/include/Acts/Vertexing/TrackDensity.hpp
acts/blob/master/Core/src/Vertexing/TrackDensity.cpp

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation