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25 // 25 //
26 // G4ConstRK4 << 26 //
>> 27 // $Id: G4ConstRK4.hh,v 1.3 2010-09-10 15:50:17 japost Exp $
>> 28 // GEANT4 tag $Name: geant4-09-04-patch-02 $
>> 29 //
>> 30 //
>> 31 // Class G4ConstRK4
27 // 32 //
28 // class description: 33 // class description:
29 // 34 //
30 // G4ConstRK4 performs the integration of one 35 // G4ConstRK4 performs the integration of one step with error calculation
31 // in constant magnetic field. The integration 36 // in constant magnetic field. The integration method is the same as in
32 // ClassicalRK4. The field value is assumed co 37 // ClassicalRK4. The field value is assumed constant for the step.
33 // This field evaluation is called only once p 38 // This field evaluation is called only once per step.
34 // G4ConstRK4 can be used only for magnetic fi 39 // G4ConstRK4 can be used only for magnetic fields.
35 40
36 // Created: J.Apostolakis, T.Nikitina - 18.09. << 41 // History:
>> 42 // - 18.09.2008 - J.Apostolakis, T.Nikitina - Created
37 // ------------------------------------------- 43 // -------------------------------------------------------------------
>> 44
38 #ifndef G4CONSTRK4_HH 45 #ifndef G4CONSTRK4_HH
39 #define G4CONSTRK4_HH 46 #define G4CONSTRK4_HH
40 47
41 #include "G4MagErrorStepper.hh" 48 #include "G4MagErrorStepper.hh"
42 #include "G4EquationOfMotion.hh" 49 #include "G4EquationOfMotion.hh"
43 #include "G4Mag_EqRhs.hh" 50 #include "G4Mag_EqRhs.hh"
44 51
45 class G4ConstRK4 : public G4MagErrorStepper 52 class G4ConstRK4 : public G4MagErrorStepper
46 { 53 {
47 public: << 54 public: // with description
48 <<
49 G4ConstRK4(G4Mag_EqRhs* EquationMotion, G <<
50 ~G4ConstRK4() override; <<
51 55
52 G4ConstRK4(const G4ConstRK4&) = delete; << 56 G4ConstRK4(G4Mag_EqRhs *EquationMotion, G4int numberOfStateVariables=8);
53 G4ConstRK4& operator=(const G4ConstRK4&) << 57 ~G4ConstRK4();
54 // Copy constructor and assignment oper <<
55 58
56 void Stepper( const G4double y[], 59 void Stepper( const G4double y[],
57 const G4double dydx[], 60 const G4double dydx[],
58 G4double h, 61 G4double h,
59 G4double yout[], 62 G4double yout[],
60 G4double yerr[] ) ov << 63 G4double yerr[] );
61 void DumbStepper( const G4double yIn[], << 64 void DumbStepper( const G4double yIn[],
62 const G4double dydx[], << 65 const G4double dydx[],
63 G4double h, << 66 G4double h,
64 G4double yOut[] ) << 67 G4double yOut[] ) ;
65 G4double DistChord() const override; << 68 G4double DistChord() const;
66 69
67 inline void RightHandSideConst(const G4d << 70 inline void RightHandSideConst(const G4double y[],
68 G4d << 71 G4double dydx[] ) const;
69 72
70 inline void GetConstField(const G4double << 73 inline void GetConstField(const G4double y[],G4double Field[]);
>> 74
>> 75 public: // without description
>> 76
>> 77 G4int IntegratorOrder() const { return 4; }
>> 78
>> 79 private:
71 80
72 G4int IntegratorOrder() const override { << 81 G4ConstRK4(const G4ConstRK4&);
>> 82 G4ConstRK4& operator=(const G4ConstRK4&);
>> 83 // Private copy constructor and assignment operator.
73 84
74 private: 85 private:
75 86
76 G4ThreeVector fInitialPoint, fMidPoint, f 87 G4ThreeVector fInitialPoint, fMidPoint, fFinalPoint;
77 // Data stored in order to find the chord 88 // Data stored in order to find the chord
78 G4double *dydxm, *dydxt, *yt; // scratch 89 G4double *dydxm, *dydxt, *yt; // scratch space - not state
79 G4double *yInitial, *yMiddle, *dydxMid, * 90 G4double *yInitial, *yMiddle, *dydxMid, *yOneStep;
80 G4Mag_EqRhs* fEq = nullptr; << 91 G4Mag_EqRhs *fEq;
81 G4double Field[3]; 92 G4double Field[3];
82 }; 93 };
83 94
84 // Inline methods 95 // Inline methods
85 96
86 inline void G4ConstRK4::RightHandSideConst(con << 97 inline void G4ConstRK4:: RightHandSideConst(const G4double y[],
87 << 98 G4double dydx[] ) const
88 { 99 {
89 100
90 G4double momentum_mag_square = y[3]*y[3] + y 101 G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5];
91 G4double inv_momentum_magnitude = 1.0 / std: 102 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
92 103
93 G4double cof = fEq->FCof()*inv_momentum_magn << 104 G4double cof =fEq->FCof()*inv_momentum_magnitude;
94 105
95 dydx[0] = y[3]*inv_momentum_magnitude; 106 dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V
96 dydx[1] = y[4]*inv_momentum_magnitude; 107 dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V
97 dydx[2] = y[5]*inv_momentum_magnitude; 108 dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V
98 109
99 dydx[3] = cof*(y[4]*Field[2] - y[5]*Field[1] 110 dydx[3] = cof*(y[4]*Field[2] - y[5]*Field[1]) ; // Ax = a*(Vy*Bz - Vz*By)
100 dydx[4] = cof*(y[5]*Field[0] - y[3]*Field[2] 111 dydx[4] = cof*(y[5]*Field[0] - y[3]*Field[2]) ; // Ay = a*(Vz*Bx - Vx*Bz)
101 dydx[5] = cof*(y[3]*Field[1] - y[4]*Field[0] 112 dydx[5] = cof*(y[3]*Field[1] - y[4]*Field[0]) ; // Az = a*(Vx*By - Vy*Bx)
102 } 113 }
103 114
104 inline void G4ConstRK4::GetConstField(const G4 << 115 inline void G4ConstRK4::GetConstField(const G4double y[],G4double B[])
105 { 116 {
106 G4double PositionAndTime[4]; << 117 G4double PositionAndTime[4];
107 118
108 PositionAndTime[0] = y[0]; 119 PositionAndTime[0] = y[0];
109 PositionAndTime[1] = y[1]; 120 PositionAndTime[1] = y[1];
110 PositionAndTime[2] = y[2]; 121 PositionAndTime[2] = y[2];
111 // Global Time 122 // Global Time
112 PositionAndTime[3] = y[7]; << 123 PositionAndTime[3] = y[7];
113 fEq -> GetFieldValue(PositionAndTime, B); << 124 fEq -> GetFieldValue(PositionAndTime, B) ;
114 } 125 }
115 126
116 #endif << 127 #endif // G4CONSTRK4_HH
117 128