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25 // 7 //
26 // G4HelixExplicitEuler implementation << 8 // $Id: G4HelixExplicitEuler.cc,v 1.1.10.1 1999/12/07 20:48:04 gunter Exp $
>> 9 // GEANT4 tag $Name: geant4-01-00 $
27 // 10 //
28 // Helix Explicit Euler: x_1 = x_0 + helix(h) <<
29 // with helix(h) being a helix piece of lengt <<
30 // Most simple approach for solving linear di <<
31 // Take the current derivative and add it to <<
32 // <<
33 // Author: W.Wander <wwc@mit.edu>, 12.09.1997 <<
34 // ------------------------------------------- <<
35 <<
36 #include "G4HelixExplicitEuler.hh" 11 #include "G4HelixExplicitEuler.hh"
37 #include "G4PhysicalConstants.hh" <<
38 #include "G4ThreeVector.hh" 12 #include "G4ThreeVector.hh"
39 13
40 G4HelixExplicitEuler::G4HelixExplicitEuler(G4M << 14 //
41 : G4MagHelicalStepper(EqRhs) << 15 // Helix Explicit Euler: x_1 = x_0 + helix(h)
42 { << 16 // with helix(h) being a helix piece of length h
43 } << 17 // W.Wander <wwc@mit.edu> 12/09/97
44 << 18 //
45 G4HelixExplicitEuler::~G4HelixExplicitEuler() <<
46 19
47 void G4HelixExplicitEuler::Stepper( const G4do << 20 // -------------------------------------------------------------------------
48 const G4do <<
49 G4do <<
50 G4do <<
51 G4do <<
52 { <<
53 // Estimation of the Stepping Angle <<
54 // <<
55 G4ThreeVector Bfld; <<
56 MagFieldEvaluate(yInput, Bfld); <<
57 <<
58 const G4int nvar = 6 ; <<
59 G4double yTemp[8], yIn[8] ; <<
60 G4ThreeVector Bfld_midpoint; <<
61 21
62 // Saving yInput because yInput and yOut can << 22 // most simple approach for solving linear differential equations.
63 // << 23 // Take the current derivative and add it to the current position.
64 for(G4int i=0; i<nvar; ++i) << 24 //
65 { <<
66 yIn[i] = yInput[i]; <<
67 } <<
68 <<
69 G4double h = Step * 0.5; <<
70 <<
71 // Do full step and two half steps <<
72 // <<
73 G4double yTemp2[7]; <<
74 AdvanceHelix(yIn, Bfld, h, yTemp2,yTemp); <<
75 MagFieldEvaluate(yTemp2, Bfld_midpoint) ; <<
76 AdvanceHelix(yTemp2, Bfld_midpoint, h, yOut) <<
77 SetAngCurve(GetAngCurve() * 2); <<
78 <<
79 // Error estimation <<
80 // <<
81 for(G4int i=0; i<nvar; ++i) <<
82 { <<
83 yErr[i] = yOut[i] - yTemp[i]; <<
84 } <<
85 } <<
86 25
87 G4double G4HelixExplicitEuler::DistChord() c << 26 void
>> 27 G4HelixExplicitEuler::DumbStepper( const G4double yIn[],
>> 28 const G4double dydx[],
>> 29 const G4double h,
>> 30 G4double yOut[])
88 { 31 {
89 // Implementation : must check whether h/R > << 32 AdvanceHelix(yIn, dydx, h, yOut);
90 // If( h/R < pi) use G4LineSection::DistL <<
91 // Else DistChord=R_helix <<
92 // <<
93 G4double distChord; <<
94 G4double Ang_curve=GetAngCurve(); <<
95 <<
96 33
97 if(Ang_curve<=pi) << 34 // NormaliseTangentVector( yOut ); // this could harm more than it helps
98 { << 35 return ;
99 distChord=GetRadHelix()*(1-std::cos(0.5*An <<
100 } <<
101 else if(Ang_curve<twopi) <<
102 { <<
103 distChord=GetRadHelix()*(1+std::cos(0.5*(t <<
104 } <<
105 else <<
106 { <<
107 distChord=2.*GetRadHelix(); <<
108 } <<
109 <<
110 return distChord; <<
111 } <<
112 <<
113 void G4HelixExplicitEuler::DumbStepper( const <<
114 <<
115 <<
116 <<
117 { <<
118 AdvanceHelix(yIn, Bfld, h, yOut); <<
119 } 36 }
120 37