//
// ********************************************************************
// * DISCLAIMER                                                       *
// *                                                                  *
// * The following disclaimer summarizes all the specific disclaimers *
// * of contributors to this software. The specific disclaimers,which *
// * govern, are listed with their locations in:                      *
// *   http://cern.ch/geant4/license                                  *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.                                                             *
// *                                                                  *
// * This  code  implementation is the  intellectual property  of the *
// * GEANT4 collaboration.                                            *
// * By copying,  distributing  or modifying the Program (or any work *
// * based  on  the Program)  you indicate  your  acceptance of  this *
// * statement, and all its terms.                                    *
// ********************************************************************
//
//
// $Id: G4El_UsualEqRhs.hh,v 1.6 2003/10/31 14:35:52 gcosmo Exp $
// GEANT4 tag $Name: geant4-06-00-patch-01 $
//
//
// class G4El_UsualEqRhs
//
// Class description:
//
// This is the standard right-hand side for equation of motion.
// The only case another is required is when using a moving reference
// frame ... or extending the class to include additional Forces,
// eg an electric field

// History:
// - Created: J. Apostolakis, January 13th 1997.
// --------------------------------------------------------------------

#ifndef G4EL_USUAL_EQRHS
#define G4EL_USUAL_EQRHS

#include "G4El_EqRhs.hh"

class G4ElectricField;

class G4El_UsualEqRhs : public G4El_EqRhs
{
   public:  // with description

     G4El_UsualEqRhs( G4ElectricField* ElField );
    ~G4El_UsualEqRhs();
       // Constructor and destructor. No actions.

     void EvaluateRhsGivenB( const G4double y[],
                             const G4double E[3],
                                   G4double dydx[] ) const;
       // Given the value of the electric field E, this function 
       // calculates the value of the derivative dydx.

     virtual void SetChargeMomentumMass( G4double particleCharge, // in e+ units
                                         G4double MomentumXc,
                                         G4double mass);

      void RightHandSide( const  G4double y[],  G4double dydx[]   ) const;

  private:

  G4double cst;
    G4double  fInvCurrentMomentumXc;   // This extra state enables us 
                                    // to save a square root in a
                                    // critical method.
};

#endif /* G4EL_USUAL_EQRHS */