Class LinearizedTrack

Class Documentation

class Acts::LinearizedTrack

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.

Public Functions

LinearizedTrack() = default

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

  • 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

LinearizedTrack(const BoundVector &paramsAtPCA, const BoundSymMatrix &parCovarianceAtPCA, const BoundSymMatrix &parWeightAtPCA, const SpacePointVector &linPoint, const SpacePointToBoundMatrix &posJacobian, const ActsMatrixD<eBoundParametersSize, 3> &momJacobian, const SpacePointVector &position, const Vector3D &momentum, const BoundVector &constTerm)

Public Members

BoundVector constantTerm = {BoundVector::Zero()}
BoundSymMatrix covarianceAtPCA = {BoundSymMatrix::Zero()}
SpacePointVector linearizationPoint = {SpacePointVector::Zero()}
Vector3D momentumAtPCA = {Vector3D::Zero()}
ActsMatrixD<eBoundParametersSize, 3> momentumJacobian{ActsMatrixD<eBoundParametersSize, 3>::Zero()}
BoundVector parametersAtPCA = {BoundVector::Zero()}
SpacePointVector positionAtPCA = {SpacePointVector::Zero()}
SpacePointToBoundMatrix positionJacobian = {SpacePointToBoundMatrix::Zero()}
BoundSymMatrix weightAtPCA = {BoundSymMatrix::Zero()}