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/// \file G4BlineEquation.hh
/// \brief Definition of the G4BlineEquation class

// --------------------------------------------------------------------
//
// G4BlineEquation
//
// Class description:
//
// This class defines the equation of motion needed to trace magnetic
// field lines in the simulation.

// --------------------------------------------------------------------
// Author: Laurent Desorgher (desorgher@phim.unibe.ch)
//         Created - 2003-10-06
// --------------------------------------------------------------------
#ifndef G4BlineEquation_h
#define G4BlineEquation_h 1

#include "G4Mag_EqRhs.hh"
#include "G4MagneticField.hh"

class G4BlineEquation : public G4Mag_EqRhs
{
  public:  // with description
    G4BlineEquation(G4MagneticField* magField);
    ~G4BlineEquation() override = default;
    // Constructor and destructor.

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

    void SetBackwardDirectionOfIntegration(G4bool abool);

  private:
    G4bool fBackward_direction = false;
    G4double fDirection = 1.;
};

#endif