The TrkMeasurementUpdator package

Introduction

The TrkMeasurementUpdator package implements the core mathematics for Kalman filter-based track fitters. It provides the calculations to add or remove a measurement to/from the state vector of a track. Inheriting from the Trk::IUpdator abstract interface, the following operations are implemented:

• addition of a measurement to a (predicted) track states in local coordinates (i.e. the Kalman filter step)
• removal of a measurement from a track state (inverse filter)
• calculation of Chi2/ndf together with the above operation as well as in separate methods
• operates on Trk::LocalParameters of any dimension (1-5) and definition
• operates also on Trk::LocalPosition

Class Overview

The TrkMeasurementUpdator package contains the following classes:

• Trk::KalmanUpdator : measurement updator in gain matrix formalism (internally using dynamic Eigen Matrices)
• Trk::KalmanUpdatorSMatrix : measurement updator in gain matrix formalism (internally using SMatrix)
• Trk::KalmanWeightUpdator : measurement updator using weighted means formalism

Author

Sebastian Fleischmann http://consult.cern.ch/xwho/people/630599
Wolfgang Liebig http://consult.cern.ch/xwho/people/485812

References

R. Fruehwirth, Application of Kalman filtering, NIM A262, 446
R. Fruehwirth, et al., Data Analysis Techniques for High-Energy Physics, 2nd ed.

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