class HepTrackHelix: public TObject

 Default constructor

 Normal constructor

 Note that the track momentum has to be given in addition via
 the member function SetP() after the ctor was called. This is
 because C++ cannot call abstract functions from inside the
 ctor, neither directly or indirectly.

 Default destructor

 Clear this object

 Print object content

 Options available:
   "covmat" - Print content of covariance matrix
   "nohead" - No header containing the variable names is
              displayed. Useful when printing a whole table
              for a list of particles

 Print information header

 Print footer

 Print helix parameters

 Print covariance matrix

 Print vtx type (there is none)

 Print Id of clone track (there is none)

 Comparison with another track by means of momentum (used for
 sorting)

 Set track momentum
 The momentum vector stored is measured in the global
 reference frame

 Convert given momentum into helix parameters

 d_vec = pca_vec - ref_vec
 sign(d) = sign((p_vec x Bz_vec) . d_vec)
 sign(d) cf ATL-SOFT-PUB-2006-004

 Get the covariance matrix of this track in Pt, eta, phi
 coordinates

 For the coordinate transformation of (Pt,eta,phi) = T*(QovP,Theta,phi) with the initial
 covariance matrix C, the transformed cov. matrix will be computed by
 Cov_new = T*C*T_transposed

 Transverse momentum

 Momentum magnitude

 Momentum z component

 Momentum 3-vector

 Polar angle of momentum vector

 Cosine of the momentum polar angle

 Pseudo-rapidity of the momentum vector

 Momentum vector azimuth

 Track is positively charged ?

 Track is negatively charged ?

 Set momentum 3-vector (in global frame)

 Covariance matrix in helix parameter expression