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Helix.h

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//======================================================================
// Auxilary class to store track paramters
//
// This class also provides methods for extracting gemometrical
// track parameters from both ordinary charged tracks and (fitted) user 
// tracks.
//
// Note that in the case of neutral tracks, the data members
// and member functions representing helix parameters 
// (IR, TL, P0, D0, Z0) become synonyms for the corresponding
// ray parameters (P, T, P0, D0, Z0)
// (Yes, this could have been implemented in a better way ...)
//
// 11/2001 K. Huettmann
//======================================================================
#ifndef _HELIX_H_
#define _HELIX_H_

#include "VfTrack.h"
#include "AlTrack.h"
#include "AlEflw.h"
#include "AlUserTrack.h"
#include "AlConcreteVertices.h"
#include "fortran_def.h"


class Helix: public VfTrack {
public:
  Helix();                           // default constructor
  Helix(QvecBase*);                   // create Helix from a track
  virtual ~Helix(){}
  virtual void setTrackParameters(QvecBase*); // set Helix parameters according to a track
  float IR()const {return _IR;}      // access to data members
  float TL()const {return _TL;}   
  float P0()const {return _P0;}
  float D0()const {return _D0;} 
  float Z0()const {return _Z0;}
  virtual float cov_matrix(int m,int n)const {return _cov_matrix(m,n);}
  virtual const HepSymMatrix& cov_matrix()const {return _cov_matrix;}
  float mass()const {return _mass;}
  int charge()const {return (int)_charge;}
private:
  // YTPAR wrapper (part of YTOP vertex fitting package)
  int w_YTPAR(float charge, float vini[3], float vvini[6], float psum[5], float vpsum[10], 
              float vpsvi[9], float trackpar[5], float vtrackpar[15]);
  float _IR;
  float _TL;   
  float _P0; 
  float _D0; 
  float _Z0;
  HepSymMatrix _cov_matrix;
  float _mass;
  float _charge;
}; 

#endif

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