Acts::AtlasBetheHeitlerApprox Class Reference

This class approximates the Bethe-Heitler distribution as a gaussian mixture. More...

#include <Acts/TrackFitting/BetheHeitlerApprox.hpp>

Inheritance diagram for Acts::AtlasBetheHeitlerApprox:

Collaboration diagram for Acts::AtlasBetheHeitlerApprox:

Classes
struct	PolyData

Public Types
using	Data = std::vector<PolyData>
	Type alias for array of polynomial data for all components.
Public Types inherited from Acts::BetheHeitlerApprox
using	Component = detail::GaussianComponent

Public Member Functions
	AtlasBetheHeitlerApprox (const Data &lowData, const Data &highData, bool lowTransform, bool highTransform, double lowLimit, double highLimit, bool clampToRange, double noChangeLimit, double singleGaussianLimit)
	Construct the Bethe-Heitler approximation description with two parameterizations, one for lower ranges, one for higher ranges.
std::size_t	maxComponents () const override
	Returns the number of components the returned mixture will have.
std::span< Component >	mixture (double xOverX0, const std::span< Component > mixture) const override
	Generates the mixture from the polynomials and reweights them, so that the sum of all weights is 1.
bool	validXOverX0 (const double xOverX0) const override
	Checks if an input is valid for the parameterization.
Public Member Functions inherited from Acts::BetheHeitlerApprox
virtual	~BetheHeitlerApprox ()=default

Static Public Member Functions
static AtlasBetheHeitlerApprox	loadFromFiles (const std::string &low_parameters_path, const std::string &high_parameters_path, double lowLimit, double highLimit, bool clampToRange, double noChangeLimit, double singleGaussianLimit)
	Loads a parameterization from a file according to the Atlas file description.

Detailed Description

This class approximates the Bethe-Heitler distribution as a gaussian mixture.

To enable an approximation for continuous input variables, the weights, means and variances are internally parametrized as a Nth order polynomial.

Todo

This class is rather inflexible: It forces two data representations, making it a bit awkward to add a single parameterization. It would be good to generalize this at some point.

Member Typedef Documentation

Data

using Acts::AtlasBetheHeitlerApprox::Data = std::vector<PolyData>

Type alias for array of polynomial data for all components.

Constructor & Destructor Documentation

AtlasBetheHeitlerApprox()

Acts::AtlasBetheHeitlerApprox::AtlasBetheHeitlerApprox	(	const Data &	lowData,
		const Data &	highData,
		bool	lowTransform,
		bool	highTransform,
		double	lowLimit,
		double	highLimit,
		bool	clampToRange,
		double	noChangeLimit,
		double	singleGaussianLimit )

Construct the Bethe-Heitler approximation description with two parameterizations, one for lower ranges, one for higher ranges.

Is it assumed that the lower limit of the high-x/x0 data is equal to the upper limit of the low-x/x0 data.

Parameters

lowData	data for the lower x/x0 range
highData	data for the higher x/x0 range
lowTransform	whether the low data need to be transformed
highTransform	whether the high data need to be transformed
lowLimit	the upper limit for the low data
highLimit	the upper limit for the high data
clampToRange	whether to clamp the input x/x0 to the allowed range
noChangeLimit	limit below which no change is applied
singleGaussianLimit	limit below which a single Gaussian is used

Member Function Documentation

loadFromFiles()

AtlasBetheHeitlerApprox Acts::AtlasBetheHeitlerApprox::loadFromFiles ( const std::string & low_parameters_path, const std::string & high_parameters_path, double lowLimit, double highLimit, bool clampToRange, double noChangeLimit, double singleGaussianLimit )

static

Loads a parameterization from a file according to the Atlas file description.

Parameters

low_parameters_path	Path to the foo.par file that stores the parameterization for low x/x0
high_parameters_path	Path to the foo.par file that stores the parameterization for high x/x0
lowLimit	the upper limit for the low x/x0-data
highLimit	the upper limit for the high x/x0-data
clampToRange	forwarded to constructor
noChangeLimit	forwarded to constructor
singleGaussianLimit	forwarded to constructor

Returns

AtlasBetheHeitlerApprox instance loaded from parameter files

maxComponents()

std::size_t Acts::AtlasBetheHeitlerApprox::maxComponents ( ) const

overridevirtual

Returns the number of components the returned mixture will have.

Returns

Number of components in the mixture

Implements Acts::BetheHeitlerApprox.

mixture()

std::span< Component > Acts::AtlasBetheHeitlerApprox::mixture ( double xOverX0, const std::span< Component > mixture ) const

overridevirtual

Generates the mixture from the polynomials and reweights them, so that the sum of all weights is 1.

Parameters

xOverX0	pathlength in terms of the radiation length
mixture	preallocated array to store the result

Returns

the potentially modified input span containing the mixture

Implements Acts::BetheHeitlerApprox.

validXOverX0()

bool Acts::AtlasBetheHeitlerApprox::validXOverX0 ( const double xOverX0 ) const

overridevirtual

Checks if an input is valid for the parameterization.

Parameters

xOverX0

pathlength in terms of the radiation length

Returns

True if x/x0 is within valid range for this parameterization

Implements Acts::BetheHeitlerApprox.