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25 // 25 //
26 // G4ExactHelixStepper implementation 26 // G4ExactHelixStepper implementation
27 // 27 //
28 // Author: J.Apostolakis, 28.01.2005. 28 // Author: J.Apostolakis, 28.01.2005.
29 // Implementation adapted from Explici 29 // Implementation adapted from ExplicitEuler by W.Wander
30 // ------------------------------------------- 30 // -------------------------------------------------------------------
31 31
32 #include "G4ExactHelixStepper.hh" 32 #include "G4ExactHelixStepper.hh"
33 #include "G4PhysicalConstants.hh" 33 #include "G4PhysicalConstants.hh"
34 #include "G4ThreeVector.hh" 34 #include "G4ThreeVector.hh"
35 #include "G4LineSection.hh" 35 #include "G4LineSection.hh"
36 36
37 G4ExactHelixStepper::G4ExactHelixStepper(G4Mag 37 G4ExactHelixStepper::G4ExactHelixStepper(G4Mag_EqRhs* EqRhs)
38 : G4MagHelicalStepper(EqRhs), 38 : G4MagHelicalStepper(EqRhs),
39 fBfieldValue(DBL_MAX, DBL_MAX, DBL_MAX) 39 fBfieldValue(DBL_MAX, DBL_MAX, DBL_MAX)
40 { 40 {
41 } 41 }
42 42
43 G4ExactHelixStepper::~G4ExactHelixStepper() = << 43 G4ExactHelixStepper::~G4ExactHelixStepper()
>> 44 {
>> 45 }
44 46
45 // ------------------------------------------- 47 // ---------------------------------------------------------------------------
46 48
47 void 49 void
48 G4ExactHelixStepper::Stepper( const G4double y 50 G4ExactHelixStepper::Stepper( const G4double yInput[],
49 const G4double*, 51 const G4double*,
50 G4double h 52 G4double hstep,
51 G4double y 53 G4double yOut[],
52 G4double y 54 G4double yErr[] )
53 { 55 {
54 const G4int nvar = 6; 56 const G4int nvar = 6;
55 57
56 G4int i; 58 G4int i;
57 G4ThreeVector Bfld_value; 59 G4ThreeVector Bfld_value;
58 60
59 MagFieldEvaluate(yInput, Bfld_value); 61 MagFieldEvaluate(yInput, Bfld_value);
60 AdvanceHelix(yInput, Bfld_value, hstep, yOut 62 AdvanceHelix(yInput, Bfld_value, hstep, yOut);
61 63
62 // We are assuming a constant field: helix i 64 // We are assuming a constant field: helix is exact
63 // 65 //
64 for(i=0; i<nvar; ++i) 66 for(i=0; i<nvar; ++i)
65 { 67 {
66 yErr[i] = 0.0 ; 68 yErr[i] = 0.0 ;
67 } 69 }
68 70
69 fBfieldValue = Bfld_value; 71 fBfieldValue = Bfld_value;
70 } 72 }
71 73
72 // ------------------------------------------- 74 // ---------------------------------------------------------------------------
73 75
74 void 76 void
75 G4ExactHelixStepper::DumbStepper( const G4doub 77 G4ExactHelixStepper::DumbStepper( const G4double yIn[],
76 G4Thre 78 G4ThreeVector Bfld,
77 G4doub 79 G4double h,
78 G4doub 80 G4double yOut[])
79 { 81 {
80 // Assuming a constant field: solution is a 82 // Assuming a constant field: solution is a helix
81 83
82 AdvanceHelix(yIn, Bfld, h, yOut); 84 AdvanceHelix(yIn, Bfld, h, yOut);
83 85
84 G4Exception("G4ExactHelixStepper::DumbSteppe 86 G4Exception("G4ExactHelixStepper::DumbStepper",
85 "GeomField0002", FatalException, 87 "GeomField0002", FatalException,
86 "Should not be called. Stepper m 88 "Should not be called. Stepper must do all the work." );
87 } 89 }
88 90
89 91
90 // ------------------------------------------- 92 // ---------------------------------------------------------------------------
91 93
92 G4double 94 G4double
93 G4ExactHelixStepper::DistChord() const 95 G4ExactHelixStepper::DistChord() const
94 { 96 {
95 // Implementation : must check whether h/R > 97 // Implementation : must check whether h/R > pi !!
96 // If( h/R < pi) DistChord=h/2*std::tan 98 // If( h/R < pi) DistChord=h/2*std::tan(Ang_curve/4)
97 // Else DistChord=R_helix 99 // Else DistChord=R_helix
98 100
99 G4double distChord; 101 G4double distChord;
100 G4double Ang_curve=GetAngCurve(); 102 G4double Ang_curve=GetAngCurve();
101 103
102 if (Ang_curve<=pi) 104 if (Ang_curve<=pi)
103 { 105 {
104 distChord=GetRadHelix()*(1-std::cos(0.5*An 106 distChord=GetRadHelix()*(1-std::cos(0.5*Ang_curve));
105 } 107 }
106 else if(Ang_curve<twopi) 108 else if(Ang_curve<twopi)
107 { 109 {
108 distChord=GetRadHelix()*(1+std::cos(0.5*(t 110 distChord=GetRadHelix()*(1+std::cos(0.5*(twopi-Ang_curve)));
109 } 111 }
110 else 112 else
111 { 113 {
112 distChord=2.*GetRadHelix(); 114 distChord=2.*GetRadHelix();
113 } 115 }
114 116
115 return distChord; 117 return distChord;
116 } 118 }
117 119
118 // ------------------------------------------- 120 // ---------------------------------------------------------------------------
119 121
120 G4int 122 G4int
121 G4ExactHelixStepper::IntegratorOrder() const 123 G4ExactHelixStepper::IntegratorOrder() const
122 { 124 {
123 return 1; 125 return 1;
124 } 126 }
125 127