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//
// $Id: G4ErrorFreeTrajParam.hh,v 1.2 2007/05/29 14:41:35 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// Class Description:
//
// Holds the 5 independent variables of the trajectory for a
// G4ErrorFreeTrajState object. It is not used for anything but for
// printing, but anyhow it is updated everytime the position and
// momentum are updated.

// History:
// - Created: Pedro Arce, September 2004
// --------------------------------------------------------------------

#ifndef G4ErrorFreeTrajParam_hh
#define G4ErrorFreeTrajParam_hh

#include "G4Point3D.hh"
#include "G4Vector3D.hh"

#include "globals.hh"
#include "G4Track.hh"

class G4ErrorFreeTrajParam
{
 public:  // with description

  G4ErrorFreeTrajParam(){}
  G4ErrorFreeTrajParam( const G4Point3D& pos, const G4Vector3D& mom );
    // build parameters from position and momentum

  virtual ~G4ErrorFreeTrajParam(){}

  void Update( const G4Track* aTrack );
    // update parameters from G4Track

  friend
    std::ostream& operator<<(std::ostream&, const G4ErrorFreeTrajParam& ts);
  
  // Set and Get methods 

  void SetParameters( const G4Point3D& pos, const G4Vector3D& mom );

  G4Vector3D GetDirection() const { return fDir;}

  G4double GetInvP() const { return fInvP; }
  G4double GetLambda() const { return fLambda; }
  G4double GetPhi() const { return fPhi; }
  G4double GetYPerp() const { return fYPerp; }
  G4double GetZPerp() const { return fZPerp; }

 private:

  G4Vector3D fDir; //direction to which YPerp, ZPerp refer
  G4double fInvP; // inverse of momentum
  G4double fLambda; // 90 - theta angle of direction
  G4double fPhi; // phi angle of direction
  G4double fYPerp; // Y coordinate
  G4double fZPerp; // Z coordinate
};

#endif
