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//
// $Id: G4Field.hh,v 1.8 2003/11/05 10:35:55 japost Exp $
// GEANT4 tag $Name: geant4-06-00-patch-01 $
//
//
// class G4Field
//
// Class description:
//
// Abstract class for any kind of Field.
// It allows any kind of field (vector, scalar, tensor and any set of them)
// to be defined by implementing the inquiry function interface.

// History:
// - Created:  John Apostolakis, 10.03.1997
// -------------------------------------------------------------------

#ifndef G4FIELD_HH
#define G4FIELD_HH

#include "G4Types.hh"

class G4Field
{
  public:  // with description

      virtual void  GetFieldValue( const  double Point[4],
                                          double *Bfield ) const = 0;
      G4Field(){;}
      virtual ~G4Field(){;}
      inline G4Field& operator = (const G4Field &p); 

     // A field signature function that can be used to insure
     // that the Equation of motion object and the G4Field object
     // have the same "field signature"?
 
      virtual G4bool   DoesFieldChangeEnergy() const= 0 ;
       //  For electric field this should be true
       //  For pure magnetic field this should be false

};

inline G4Field& G4Field::operator = (const G4Field &p)
{
  if (&p != this) { *this = p; }
  return *this;
}

#endif /* G4FIELD_HH */