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25 //
26 // G4TMagFieldEquation
27 //
28 // Class description:
29 //
30 // Templated version of motion of quadrupole magnetic field.
31 // Enables testing of inlined code for field, equation, stepper, driver,
32 // avoiding all virtual calls.
33 //
34 // --------------------------------------------------------------------
35 // Created: Josh Xie (Google Summer of Code 2014 )
36 // Adapted from G4QuadrupoleMagField ( of June 2014 .... )
37 //
38
39 #ifndef G4T_QUADRUPOLE_MAGFIELD_HH
40 #define G4T_QUADRUPOLE_MAGFIELD_HH
41
42 #include "G4ThreeVector.hh"
43 #include "G4RotationMatrix.hh"
44 #include "G4MagneticField.hh"
45
46 static G4RotationMatrix IdentityMatrix;
47
48 class G4TQuadrupoleMagField : public G4MagneticField
49 {
50 public: // with description
51
52 G4TQuadrupoleMagField(G4double pGradient)
53 {
54 fGradient = pGradient ;
55 fOrigin = G4ThreeVector( 0.0, 0.0, 0.0) ;
56 fpMatrix = &IdentityMatrix;
57 }
58
59 G4TQuadrupoleMagField(G4double pGradient,
60 G4ThreeVector pOrigin,
61 G4RotationMatrix* pMatrix)
62 {
63 fGradient = pGradient ;
64 fOrigin = pOrigin ;
65 fpMatrix = pMatrix ;
66 }
67
68 virtual ~G4TQuadrupoleMagField() {;}
69
70 inline void GetFieldValue(const G4double y[7],
71 G4double B[3] ) const
72 {
73 G4ThreeVector r_global = G4ThreeVector(
74 y[0] - fOrigin.x(),
75 y[1] - fOrigin.y(),
76 y[2] - fOrigin.z());
77
78 G4ThreeVector r_local = G4ThreeVector(
79 fpMatrix->colX() * r_global,
80 fpMatrix->colY() * r_global,
81 fpMatrix->colZ() * r_global);
82
83 G4ThreeVector B_local = G4ThreeVector(
84 fGradient * r_local.y(),
85 fGradient * r_local.x(),
86 0);
87
88 G4ThreeVector B_global = G4ThreeVector(
89 fpMatrix->inverse().rowX() * B_local,
90 fpMatrix->inverse().rowY() * B_local,
91 fpMatrix->inverse().rowZ() * B_local);
92
93 B[0] = B_global.x() ;
94 B[1] = B_global.y() ;
95 B[2] = B_global.z() ;
96 }
97
98 G4TQuadrupoleMagField* Clone() const
99 {
100 //TODO: Can the fpMatrix be shared??
101 return new G4TQuadrupoleMagField(this->fGradient,
102 this->fOrigin,
103 this->fpMatrix);
104 }
105
106 private:
107
108 G4double fGradient;
109 G4ThreeVector fOrigin;
110 G4RotationMatrix* fpMatrix;
111 };
112 #endif
113
114