GeneralBrokenLines
Rev:70

For a track with an initial trajectory from a prefit of the measurements (internal seed) or an external prediction (external seed) the description of multiple scattering is added by offsets in a local system. Along the initial trajectory points are defined with can describe a measurement or a (thin) scatterer or both. Measurements are arbitrary functions of the local track parameters at a point (e.g. 2D: position, 4D: slope+position). The refit provides corrections to the local track parameters (in the local system) and the corresponding covariance matrix at any of those points. Outliers can be downweighted by use of Mestimators.
The broken lines trajectory is defined by (2D) offsets at the first and last point and all points with a scatterer. The prediction for a measurement is obtained by interpolation of the enclosing offsets and for triplets of adjacent offsets kink angles are determined. This requires for all points the jacobians for propagation to the previous and next offset. These are calculated from the pointtopoint jacobians along the initial trajectory.
Additional local or global parameters can be added and the trajectories can be written to special binary files for calibration and alignment with MillepedeII. (V. Blobel, NIM A, 566 (2006), pp. 513).
The conventions for the coordinate systems follow: Derivation of Jacobians for the propagation of covariance matrices of track parameters in homogeneous magnetic fields A. Strandlie, W. Wittek, NIM A, 566 (2006) 687698.
CALL gblini(..)
CALL gbladp(..)
CALL gbladm(..)
CALL gbladl(..)
CALL gbladg(..)
CALL gblads(..)
CALL gbladx(..)
CALL gblfit(..)
CALL gblres(..)
CALL gblmp2(..)
Linear algebra routines are taken from MillepedeII (by V. Blobel, University Hamburg). Only 2D (or 1D) measurements are implemented.