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//
// G4Mag_EqRhs
//
// Class description:
//
// The "standard" equation of motion of a particle in a pure magnetic field.
// Other that might be required are:
//     i) is when using a moving reference frame ... or
//    ii) extending for other forces, e.g. an electric field

// Created: J.Apostolakis, CERN - 13.01.1997
// --------------------------------------------------------------------
#ifndef G4MAG_EQRHS_HH
#define G4MAG_EQRHS_HH

#include "G4Types.hh"
#include "G4ChargeState.hh"
#include "G4EquationOfMotion.hh"

class G4MagneticField;

class G4Mag_EqRhs : public G4EquationOfMotion
{
  public: // with description

     G4Mag_EqRhs(G4MagneticField* magField);
     virtual ~G4Mag_EqRhs();
       // Constructor and destructor. No actions.

     virtual void EvaluateRhsGivenB( const G4double y[],
                                     const G4double B[3],
                                           G4double dydx[] ) const = 0;
       // Given the value of the  field "B", this function 
       // calculates the value of the derivative dydx.
       // This is the _only_ function a subclass must define.
       // The other two functions use Rhs_givenB.

     inline G4double FCof() const { return fCof_val; }

     virtual void SetChargeMomentumMass( G4ChargeState particleCharge,
                                         G4double MomentumXc,
                                         G4double mass );
  private:

     G4double fCof_val = 0.0;

     static const G4double fUnitConstant;     // Set to 0.299792458
       // Coefficient in the Lorentz motion equation (Lorentz force), if the
       // magnetic field B is in Tesla, the particle charge in units of the 
       // elementary (positron?) charge, the momentum P in MeV/c, and the
       // space coordinates and path along the trajectory in mm.
};

#endif