| Geant4 Cross Reference |
1 //
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25 //
26 // G4HelixImplicitEuler implementation
27 //
28 // Helix Implicit Euler:
29 // x_1 = x_0 + 1/2 * ( helix(h,t_0,x_0)
30 // + helix(h,t_0+h,x_0+helix(h,t0,x0) ) )
31 // Second order solver.
32 // Take the current derivative and add it to the current position.
33 // Take the output and its derivative. Add the mean of both derivatives
34 // to form the final output
35 //
36 // Author: W.Wander <wwc@mit.edu>, 03/11/1998
37 // -------------------------------------------------------------------------
38
39 #include "G4HelixImplicitEuler.hh"
40 #include "G4ThreeVector.hh"
41
42 G4HelixImplicitEuler::G4HelixImplicitEuler(G4Mag_EqRhs *EqRhs)
43 : G4MagHelicalStepper(EqRhs)
44 {
45 }
46
47 G4HelixImplicitEuler::~G4HelixImplicitEuler() = default;
48
49 void
50 G4HelixImplicitEuler::DumbStepper( const G4double yIn[],
51 G4ThreeVector Bfld,
52 G4double h,
53 G4double yOut[])
54 {
55 const G4int nvar = 6 ;
56 G4double yTemp[6], yTemp2[6];
57 G4ThreeVector Bfld_endpoint;
58
59 // Step forward like in the explicit euler case
60 //
61 AdvanceHelix( yIn, Bfld, h, yTemp);
62
63 // now obtain the new field value at the new point
64 //
65 MagFieldEvaluate(yTemp, Bfld_endpoint);
66
67 // and also advance along a helix for this field value
68 //
69 AdvanceHelix( yIn, Bfld_endpoint, h, yTemp2);
70
71 // we take the average
72 //
73 for( G4int i = 0; i < nvar; ++i )
74 {
75 yOut[i] = 0.5 * ( yTemp[i] + yTemp2[i] );
76 }
77
78 // NormaliseTangentVector( yOut );
79 }
80