class AliTRDtrackletOflHelper: public TObject

 Default constructor

 Copy constructor

 Clean helper

 Allocate new clusters for this helper.  If a subset of clusters is to be allocated
 this can be specified via the identifier "groupId" which have to be compared
 with individual elements in the array "mark".

 Return total no. of clusters in helper

 Allocate clusters for this helper.  If a subset of clusters is to be allocated
 this can be specified via the identifier "groupId" which have to be compared
 with individual elements in the array "mark".

 Return no. of clusters allocated

 Classify topology and return classification code
 0 - normal tracklet
 1 - delta ray candidate
 2 - secondary candidate
 3 - "elephant" candidate
 4 - unknown topology

  Find clusters produced by large fluctuations of energy deposits
  Largest charge and well separation from neighbors

 Fit tracklet in Pad System of Reference [PSR] to avoid uncertainty related to
 Lorentz angle correction

 Iterative robust tracklet fit

 Wrapper for clusters attach to this for static Fit function

 Calculate Rotation[r], Mean y[m] (at radial position [xm]) and Sigma[s] (of a gaussian distribution in the tracklet [SR])
 for clusters attach to this helper. The Rotation and Mean are calculated without tilt correction option.
 It returns the number of clusters in 1 sigma cut.

 Calculate total charge NOT normalized to inclination

 Calculate mean uncertainty of clusters

 Segmentation of clusters in the tracklet roads

 The user supply the coordinates of the clusters (x,y) and their number "n". Also
 The array "Index" has to be allocated by the user with a size equal or larger than "n".
 On return the function returns the number of segments found and the array "Index" i-th element
 is filled with the index of the tracklet segment to which the i-th cluster was assigned too.

 Observation
 The parameter which controls the segmentation is set inside the function "kGapSize" and it is used
 for both "x" and "y" segmentations. An improvement can be a parametrization as function of angle of
 incidence.

 author:
 Alex Bercuci <a.bercuci@gsi.de>

 Set first time bin and total number of time bins corresponding to clusters
 in chamber based on the calibrated info "t0" and drift velocity "vd"

 Visualization support. Draw this tracklet segment