Reconstruction/MdcPatRec/TrkBase/include/TrkBase/TrkKalDeriv.h

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//--------------------------------------------------------------------------
// File and Version Information:
//      $Id: TrkKalDeriv.h,v 1.2 2006/03/28 01:02:36 zhangy Exp $
//
// Description:  Pure abstract class adding derrivative functions needed
//  for kalman tracking.  This shouldn't be inherited directly, but is
//  instead brought in either through TrkSimpTraj or TrkDifPieceTraj.
//
// Environment:
//      Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author(s): Dave Brown 6/2/97
//
//------------------------------------------------------------------------
 
#ifndef TRKKALDERIV_H
#define TRKKALDERIV_H
#include "CLHEP/Matrix/Matrix.h"
 
using CLHEP::HepMatrix;
 
//  Enum defining deflection directions: theta1 is deflection in the
//  rho-z plane, theta2 is deflection in the phi direction.
enum deflectDirection { theta1 = 0, theta2 };
 
class TrkKalDeriv {
public:
  // FIXME: this is a baseclass, therefore it should have a virtual d'tor...
  // virtual ~TrkKalDeriv() {} ;
  //  Change in param WRT change in direction
  virtual HepMatrix derivDeflect( double fltlen, deflectDirection idir ) const = 0;
  // change in param WRT change in transverse position.  This is another
  // effect of multiple scattering, only substantial for thick materials
  virtual HepMatrix derivDisplace( double fltlen, deflectDirection idir ) const = 0;
  //  Similair function for the parameter change WRT change in fractional momentum
  virtual HepMatrix derivPFract( double fltlen ) const = 0;
};
 
#endif