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geant4/source/geometry/magneticfield/include/G4HelixSimpleRunge.hh
2025-12-05 08:54:02 +01:00

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// G4HelixSimpleRunge
//
// Class description:
//
// Helix Simple Runge-Kutta stepper for magnetic field:
// x_1 = x_0 + h * ( dx( t_0+h/2, x_0 + h/2 * dx( t_0, x_0) ) )
//
// Second order solver.
// Take the derivative at a position to be assumed at the middle of the
// Step and add it to the current position.
// Author: W.Wander (MIT), 03.12.1998
// -------------------------------------------------------------------
#ifndef G4HELIXSIMPLERUNGE_HH
#define G4HELIXSIMPLERUNGE_HH
#include "G4MagHelicalStepper.hh"
/**
* @brief G4HelixSimpleRunge implements a simple Helix stepper for magnetic
* field with 2nd order solver.
*/
class G4HelixSimpleRunge : public G4MagHelicalStepper
{
public:
/**
* Constructor for G4HelixSimpleRunge.
* @param[in] EqRhs Pointer to the provided equation of motion.
*/
G4HelixSimpleRunge(G4Mag_EqRhs* EqRhs);
/**
* Default Destructor.
*/
~G4HelixSimpleRunge() override = default;
/**
* The stepper function for the integration.
* @param[in] y Starting values array of integration variables.
* @param[in] Bfld The field vector.
* @param[in] h The given step size.
* @param[out] yout Integration output.
*/
void DumbStepper( const G4double y[],
G4ThreeVector Bfld,
G4double h,
G4double yout[] ) override;
/**
* Returns the order, 2, of integration.
*/
inline G4int IntegratorOrder() const override { return 2; }
/**
* Returns the stepper type-ID, "kHelixSimpleRunge".
*/
inline G4StepperType StepperType() const override { return kHelixSimpleRunge; }
};
#endif