Reconstruction/MdcPatRec/MdcRecoUtil/include/MdcRecoUtil/DifFourVector.h

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//--------------------------------------------------------------------------
// File and Version Information:
//  $Id: DifFourVector.h,v 1.3 2009/12/23 02:59:56 zhangy Exp $
//
// Description:
//  Class Header for |DifVector|
//      A 4-vector based on differential numbers
//
// Environment:
//  Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author List:
//  A. Snyder
//
// Copyright Information:
//  Copyright (C) 2002  SLAC
//
// History:
//  Migration for BESIII MDC
//
//------------------------------------------------------------------------
 
#ifndef DifFourVector_H
#define DifFourVector_H
 
#include <vector>
 
#include "CLHEP/Vector/ThreeVector.h"
#include "MdcRecoUtil/DifNumber.h"
#include "MdcRecoUtil/DifVector.h"
#include <iosfwd>
class DifRotation;
using CLHEP::Hep3Vector;
class DifFourVector {
 
public:
  // constructors
  DifFourVector(); // null - default
  DifFourVector    // construct from components
      ( const DifNumber& mass, const DifVector& p );
  DifFourVector // construct from components
      ( const double& mass, const DifVector& p );
 
  DifFourVector( const DifFourVector& v ); // copy
 
  // destructor
  ~DifFourVector() {} // destroy
 
  // given error on parameters calculate error on vector
  HepSymMatrix errorMatrix // caclulate error matrix
      ( const HepSymMatrix& e ) const;
 
  // give jacobian transformation matrix wrt independent parameters;
  HepMatrix jacobian() const;
 
  // operators
  inline DifFourVector& operator+=( const DifFourVector& v );
  inline DifFourVector& operator-=( const DifFourVector& v );
  inline DifFourVector& operator=( const DifFourVector& v );
  inline DifFourVector  operator-() const;
 
  inline friend DifFourVector operator+ // vector sum
      ( const DifFourVector& a, const DifFourVector& b );
  inline friend DifFourVector operator- // vector difference
      ( const DifFourVector& a, const DifFourVector& b );
  inline friend DifNumber operator* // scalar product
      ( const DifFourVector& a, const DifFourVector& b );
 
  // access
  inline int       nPar() const; // return number of params
  inline DifVector direction() const;
  inline DifNumber pMag() const { return P.length(); }
  inline DifNumber massSq() const { return E * E - P * P; }
  inline DifNumber mass() const {
    DifNumber temp = massSq();
    if ( temp >= 0 ) return sqrt( temp );
    return -sqrt( -massSq() );
  }
 
  // i/o
  void print( /*std::ostream& o*/ ) const; // print out
 
  // manipulations
 
  // misc
  inline DifFourVector& zeroDerivatives(); // zero derivatives
 
  // boost
 
  void boostTo( const DifFourVector& );
  void boostFrom( const DifFourVector& );
 
  void boostToMe( std::vector<DifFourVector*>& listToBoost ) const;
  void boostFromMe( std::vector<DifFourVector*>& listToBoost ) const;
 
  // algebra
 
  // data members - public .. yes, folks that's intentional!
public:
  // energy-momentum components of a 4-vector
 
  DifNumber E; // energy-like component
  DifVector P; // momentum-like compoent
};
 
// io
/*SKIP
inline std::ostream& operator<<(std::ostream& o,const DifFourVector& n) {
  n.print(o);
  return o;
}
*/
#include "MdcRecoUtil/DifFourVector.icc"
 
#endif