include/Geant4/G4HelixExplicitEuler.hh

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0025 //
0026 // G4HelixExplicitEuler
0027 //
0028 // Class description:
0029 //
0030 // Helix Explicit Euler: x_1 = x_0 + helix(h)
0031 // with helix(h) being a helix piece of length h.
0032 // A simple approach for solving linear differential equations.
0033 // Take the current derivative and add it to the current position.
0034
0035 // Author: W.Wander (MIT), 12.09.1997
0036 // -------------------------------------------------------------------
0037 #ifndef G4HELIXEXPLICITEULER_HH
0038 #define G4HELIXEXPLICITEULER_HH
0039
0040 #include "G4MagHelicalStepper.hh"
0041
0042 /**
0043  * @brief G4HelixExplicitEuler implements an Explicit Euler stepper for
0044  * magnetic field: x_1 = x_0 + helix(h), with helix(h) being a helix piece
0045  * of length h. A simple approach for solving linear differential equations.
0046  * Takes the current derivative and adds it to the current position.
0047  */
0048
0049 class G4HelixExplicitEuler : public G4MagHelicalStepper
0050 {
0051   public:
0052
0053     /**
0054      * Constructor for G4HelixExplicitEuler.
0055      *  @param[in] EqRhs Pointer to the provided equation of motion.
0056      */
0057     G4HelixExplicitEuler(G4Mag_EqRhs* EqRhs);
0058
0059     /**
0060      * Default Destructor.
0061      */
0062     ~G4HelixExplicitEuler() override = default;
0063
0064     /**
0065      * The stepper function for the integration.
0066      *  @param[in] y Starting values array of integration variables.
0067      *  @param[in] na Not used.
0068      *  @param[in] h The given step size.
0069      *  @param[out] yout Integration output.
0070      *  @param[out] yerr Integration error.
0071      */
0072     void Stepper( const G4double y[],
0073                   const G4double* na,
0074                         G4double h,
0075                         G4double yout[],
0076                         G4double yerr[]  ) override;
0077
0078     /**
0079      * The stepper function for the integration.
0080      *  @param[in] y Starting values array of integration variables.
0081      *  @param[in] Bfld Derivatives array.
0082      *  @param[in] h The given step size.
0083      *  @param[out] yout Integration output.
0084      */
0085     void DumbStepper( const G4double y[],
0086                             G4ThreeVector Bfld,
0087                             G4double h,
0088                             G4double yout[]) override;
0089
0090     /**
0091      * Returns the distance from chord line.
0092      */
0093     G4double DistChord() const override;
0094
0095     /**
0096      * Returns the order, 1, of integration.
0097      */
0098     inline G4int IntegratorOrder() const override { return 1; }
0099
0100     /**
0101      * Returns the stepper type-ID, "kHelixExplicitEuler".
0102      */
0103     inline G4StepperType StepperType() const override { return kHelixExplicitEuler; }
0104 };
0105
0106 #endif