include/Geant4/G4SimpleHeum.hh

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0025 //
0026 // G4SimpleHeum
0027 //
0028 // Class description:
0029 //
0030 // Simple Heum stepper for magnetic field:
0031 //        x_1 = x_0  +
0032 //              h * 1/4 * dx(t0,x0)  +
0033 //                  3/4 * dx(t0+2/3*h, x0+2/3*h*(dx(t0+h/3,x0+h/3*dx(t0,x0))))
0034 //
0035 // Third order solver.
0036
0037 // Author: W.Wander (MIT), 12.09.1997
0038 // -------------------------------------------------------------------
0039 #ifndef G4SIMPLEHEUM_HH
0040 #define G4SIMPLEHEUM_HH
0041
0042 #include "G4MagErrorStepper.hh"
0043
0044 /**
0045  * @brief G4SimpleHeum implements a simple Heum stepper for magnetic field
0046  * with 3rd order solver.
0047  */
0048
0049 class G4SimpleHeum : public G4MagErrorStepper
0050 {
0051   public:
0052
0053     /**
0054      * Constructor for G4SimpleHeum.
0055      *  @param[in] EqRhs Pointer to the provided equation of motion.
0056      *  @param[in] num_variables The number of integration variables.
0057      */
0058     G4SimpleHeum(G4EquationOfMotion* EqRhs,
0059                  G4int num_variables = 6);
0060
0061     /**
0062      * Destructor.
0063      */
0064     ~G4SimpleHeum() override;
0065
0066     /**
0067      * Copy constructor and assignment operator not allowed.
0068      */
0069     G4SimpleHeum(const G4SimpleHeum&) = delete;
0070     G4SimpleHeum& operator=(const G4SimpleHeum&) = delete;
0071
0072     /**
0073      * The stepper for the Runge Kutta integration, but performing a 'dump' step
0074      * without error calculation.
0075      *  @param[in] y Starting values array of integration variables.
0076      *  @param[in] dydx Derivatives array.
0077      *  @param[in] h The given step size.
0078      *  @param[out] yout Integration output.
0079      */
0080     void DumbStepper( const G4double y[],
0081                       const G4double dydx[],
0082                             G4double h,
0083                             G4double yout[] ) override;
0084
0085     /**
0086      * Returns the order, 3, of integration.
0087      */
0088     inline G4int IntegratorOrder() const override { return 3; }
0089
0090     /**
0091      * Returns the stepper type-ID, "kSimpleHeum".
0092      */
0093     inline G4StepperType StepperType() const override { return kSimpleHeum; }
0094
0095   private:
0096
0097     G4int fNumberOfVariables = 0;
0098
0099     G4double* dydxTemp = nullptr;
0100     G4double* dydxTemp2 = nullptr;
0101     G4double* yTemp = nullptr;
0102     G4double* yTemp2 = nullptr;
0103 };
0104
0105 #endif