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geant4/source/geometry/magneticfield/include/G4HelixExplicitEuler.hh
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// G4HelixExplicitEuler
//
// Class description:
//
// Helix Explicit Euler: x_1 = x_0 + helix(h)
// with helix(h) being a helix piece of length h.
// A simple approach for solving linear differential equations.
// Take the current derivative and add it to the current position.
// Author: W.Wander (MIT), 12.09.1997
// -------------------------------------------------------------------
#ifndef G4HELIXEXPLICITEULER_HH
#define G4HELIXEXPLICITEULER_HH
#include "G4MagHelicalStepper.hh"
/**
* @brief G4HelixExplicitEuler implements an Explicit Euler stepper for
* magnetic field: x_1 = x_0 + helix(h), with helix(h) being a helix piece
* of length h. A simple approach for solving linear differential equations.
* Takes the current derivative and adds it to the current position.
*/
class G4HelixExplicitEuler : public G4MagHelicalStepper
{
public:
/**
* Constructor for G4HelixExplicitEuler.
* @param[in] EqRhs Pointer to the provided equation of motion.
*/
G4HelixExplicitEuler(G4Mag_EqRhs* EqRhs);
/**
* Default Destructor.
*/
~G4HelixExplicitEuler() override = default;
/**
* The stepper function for the integration.
* @param[in] y Starting values array of integration variables.
* @param[in] na Not used.
* @param[in] h The given step size.
* @param[out] yout Integration output.
* @param[out] yerr Integration error.
*/
void Stepper( const G4double y[],
const G4double* na,
G4double h,
G4double yout[],
G4double yerr[] ) override;
/**
* The stepper function for the integration.
* @param[in] y Starting values array of integration variables.
* @param[in] Bfld Derivatives array.
* @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 distance from chord line.
*/
G4double DistChord() const override;
/**
* Returns the order, 1, of integration.
*/
inline G4int IntegratorOrder() const override { return 1; }
/**
* Returns the stepper type-ID, "kHelixExplicitEuler".
*/
inline G4StepperType StepperType() const override { return kHelixExplicitEuler; }
};
#endif