include/Geant4/G4HelixImplicitEuler.hh

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0025 //
0026 // G4HelixImplicitEuler
0027 //
0028 // Class description:
0029 //
0030 //  Helix Implicit Euler stepper for magnetic field:
0031 //        x_1 = x_0 + 1/2 * ( helix(h,t_0,x_0)
0032 //                          + helix(h,t_0+h,x_0+helix(h,t0,x0) ) )
0033 //  Second order solver.
0034 //  Take the current derivative and add it to the current position.
0035 //  Take the output and its derivative. Add the mean of both derivatives
0036 //  to form the final output.
0037
0038 // Author: W.Wander (MIT), 03.11.1998
0039 // -------------------------------------------------------------------
0040 #ifndef G4HELIXIMPLICITEULER_HH
0041 #define G4HELIXIMPLICITEULER_HH
0042
0043 #include "G4MagHelicalStepper.hh"
0044
0045 /**
0046  * @brief G4HelixImplicitEuler implements a helix implicit Euler
0047  * stepper for magnetic field with 2nd order solver.
0048  */
0049
0050 class G4HelixImplicitEuler : public G4MagHelicalStepper
0051 {
0052   public:
0053
0054     /**
0055      * Constructor for G4HelixImplicitEuler.
0056      *  @param[in] EqRhs Pointer to the provided equation of motion.
0057      */
0058     G4HelixImplicitEuler(G4Mag_EqRhs* EqRhs);
0059
0060     /**
0061      * Default Destructor.
0062      */
0063     ~G4HelixImplicitEuler() override = default;
0064
0065     /**
0066      * The stepper function for the integration.
0067      *  @param[in] y Starting values array of integration variables.
0068      *  @param[in] Bfld Derivatives array.
0069      *  @param[in] h The given step size.
0070      *  @param[out] yout Integration output.
0071      */
0072     void DumbStepper( const G4double y[],
0073                             G4ThreeVector Bfld,
0074                             G4double h,
0075                             G4double yout[] ) override;
0076
0077     /**
0078      * Returns the order, 2, of integration.
0079      */
0080     inline G4int IntegratorOrder() const override { return 2; }
0081
0082     /**
0083      * Returns the stepper type-ID, "kHelixImplicitEuler".
0084      */
0085     inline G4StepperType StepperType() const override { return kHelixImplicitEuler; }
0086 };
0087
0088 #endif