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ATLAS Offline Software
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ATLAS Offline Software
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The package TrkFitterUtils provides two types of classes: definitions which are in use by the interfaces for track fits and internal data or helper classes for one or several track fitter implementations.
Definitions are provided by FitterTypes.h, namely the typedefs for objects commonly used in track fitting, like MeasurementSet, PrepRawDataSet and RIO_OnTrackSet (= vectors of this kind of object) and the switch to control outlier removal. These definitions are used in the ITrackFitter interface as well as in some of the helper classes here - therefore the definitions are provided here and not inside TrkFitterInterfaces. To allow a more refined understanding of problematic fits than a simple good-fail, a class FitterStatusCode.h is provided to extend the Gaudi StatusCode, describing different error conditions (of mainly iterative track fit algorithms).
The classes DNA_MaterialEffects.h and ProtoTrackStateOnSurface.h are designed for internal use by track fitters when the trajectory is still under formation (i.e. track parameters added, outliers flagged). When the fitter gets ready, its objects can be quickly transferred onto a Trk::Track. Code to access high-level information about a list of Proto-TSoS, i.e. a trajectory candidate, is contained in ProtoTrajectoryUtility.h, allowing the fitter implementations to be relatively free of track-state-management code which is not directly related to the individual fitting algorithms.
Some of the fitter interface methods, for example the fit of a track extension, exist for convenience only and do not always necessitate a stand-alone algorithmic implementation in addition to what is already used for the core method (fit of a list of measurements). Instead, the track or track extension input should be dissolved back into a list of measurements and the core interface called. For that purpose the TrackFitInputPreparator.h is provided.
This package also holds one more comparison functor for sorting, MeasBaseIndexComparisonFunction.h, which uses an index to keeps a link to the original position of a measurement on a trajectory before sorting. This is needed for using measurements as sorting criterium but maintaining access to e.g. the TrackState holding the current measurement.
Full details can be found under the "Class List" section. The ITrackFitter interface, which first had been part of this package, has been moved to a separate package: TrkFitterInterfaces.
1.8.18