Acts::LinearizedTrack Class Reference

Class for linear expansion of track parameters in vicinity of vertex. More...

#include <Acts/Vertexing/LinearizedTrack.hpp>

Public Member Functions
	LinearizedTrack ()=default
	LinearizedTrack (const BoundVector &paramsAtPCA, const BoundSquareMatrix &parCovarianceAtPCA, const BoundSquareMatrix &parWeightAtPCA, const Vector4 &linPoint, const ActsMatrix< eBoundSize, 4 > &posJacobian, const ActsMatrix< eBoundSize, 3 > &momJacobian, const Vector4 &position, const Vector3 &momentum, const BoundVector &constTerm)
	Constructor taking perigee parameters and covariance matrix of track propagated to closest approach (PCA) of linearization point, position and momentum Jacobian and const term.

Public Attributes
BoundVector	constantTerm {BoundVector::Zero()}
	Constant term in linearized track equation.
BoundSquareMatrix	covarianceAtPCA {BoundSquareMatrix::Zero()}
	Covariance matrix of track parameters at PCA.
Vector4	linearizationPoint {Vector4::Zero()}
	4D point where track was linearized for vertex fitting
Vector3	momentumAtPCA {Vector3::Zero()}
	3D momentum vector at point of closest approach
ActsMatrix< eBoundSize, 3 >	momentumJacobian {ActsMatrix<eBoundSize, 3>::Zero()}
	Jacobian of track parameters w.r.t. track momentum.
BoundVector	parametersAtPCA {BoundVector::Zero()}
	Track parameters at the point of closest approach.
Vector4	positionAtPCA {Vector4::Zero()}
	4D position of track at point of closest approach
ActsMatrix< eBoundSize, 4 >	positionJacobian {ActsMatrix<eBoundSize, 4>::Zero()}
	Jacobian of track parameters w.r.t. vertex position.
BoundSquareMatrix	weightAtPCA {BoundSquareMatrix::Zero()}
	Weight matrix (inverse covariance) at PCA.

Detailed Description

Class for linear expansion of track parameters in vicinity of vertex.

The measurement equation is linearized in the following way:

F_k= D_k (x_k - x_0k) + E_k (p_k - p_0k) + F^0_k

where F_k are the parameters at perigee nearest to the linearization point, x_k is the position of the vertex, p_k the track momentum at the vertex, and F^0_k is the constant term of expansion. D_k and E_k are matrices of derivatives, denoted hereafter as "positionJacobian" and "momentumJacobian" respectively.

Constructor & Destructor Documentation

LinearizedTrack() [1/2]

Acts::LinearizedTrack::LinearizedTrack ( )

default

LinearizedTrack() [2/2]

Acts::LinearizedTrack::LinearizedTrack	(	const BoundVector &	paramsAtPCA,
		const BoundSquareMatrix &	parCovarianceAtPCA,
		const BoundSquareMatrix &	parWeightAtPCA,
		const Vector4 &	linPoint,
		const ActsMatrix< eBoundSize, 4 > &	posJacobian,
		const ActsMatrix< eBoundSize, 3 > &	momJacobian,
		const Vector4 &	position,
		const Vector3 &	momentum,
		const BoundVector &	constTerm )

Constructor taking perigee parameters and covariance matrix of track propagated to closest approach (PCA) of linearization point, position and momentum Jacobian and const term.

Parameters

paramsAtPCA	Parameters at point of closest approach
parCovarianceAtPCA	Parameter covariance matrix at point of closest approach
parWeightAtPCA	The weight at the point of closest approach
linPoint	Linearization point
posJacobian	Position jacobian
momJacobian	Momentum jacobian
position	Position at point of closest approach
momentum	Momentum at point of closest approach
constTerm	Constant term in taylor expansion

Member Data Documentation

constantTerm

BoundVector Acts::LinearizedTrack::constantTerm {BoundVector::Zero()}

Constant term in linearized track equation.

covarianceAtPCA

BoundSquareMatrix Acts::LinearizedTrack::covarianceAtPCA {BoundSquareMatrix::Zero()}

Covariance matrix of track parameters at PCA.

linearizationPoint

Vector4 Acts::LinearizedTrack::linearizationPoint {Vector4::Zero()}

4D point where track was linearized for vertex fitting

momentumAtPCA

Vector3 Acts::LinearizedTrack::momentumAtPCA {Vector3::Zero()}

3D momentum vector at point of closest approach

momentumJacobian

ActsMatrix<eBoundSize, 3> Acts::LinearizedTrack::momentumJacobian {ActsMatrix<eBoundSize, 3>::Zero()}

Jacobian of track parameters w.r.t. track momentum.

parametersAtPCA

BoundVector Acts::LinearizedTrack::parametersAtPCA {BoundVector::Zero()}

Track parameters at the point of closest approach.

positionAtPCA

Vector4 Acts::LinearizedTrack::positionAtPCA {Vector4::Zero()}

4D position of track at point of closest approach

positionJacobian

ActsMatrix<eBoundSize, 4> Acts::LinearizedTrack::positionJacobian {ActsMatrix<eBoundSize, 4>::Zero()}

Jacobian of track parameters w.r.t. vertex position.

weightAtPCA

BoundSquareMatrix Acts::LinearizedTrack::weightAtPCA {BoundSquareMatrix::Zero()}

Weight matrix (inverse covariance) at PCA.