Geant4  v4-10.4-release
G4HelixImplicitEuler.cc
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27 // $Id: G4HelixImplicitEuler.cc 66356 2012-12-18 09:02:32Z gcosmo$
28 //
29 //
30 // Helix Implicit Euler:
31 // x_1 = x_0 + 1/2 * ( helix(h,t_0,x_0)
32 // + helix(h,t_0+h,x_0+helix(h,t0,x0) ) )
33 // Second order solver.
34 // Take the current derivative and add it to the current position.
35 // Take the output and its derivative. Add the mean of both derivatives
36 // to form the final output
37 //
38 // W.Wander <wwc@mit.edu> 12/09/97
39 //
40 // -------------------------------------------------------------------------
41
42 #include "G4HelixImplicitEuler.hh"
43 #include "G4ThreeVector.hh"
44
45 void
47  G4ThreeVector Bfld,
48  G4double h,
49  G4double yOut[])
50 {
51  const G4int nvar = 6 ;
52  G4double yTemp[6], yTemp2[6];
53  G4ThreeVector Bfld_endpoint;
54
55  G4int i;
56
57  // Step forward like in the explicit euler case
58  AdvanceHelix( yIn, Bfld, h, yTemp);
59
60  // now obtain the new field value at the new point
61  MagFieldEvaluate(yTemp, Bfld_endpoint);
62
63  // and also advance along a helix for this field value
64  AdvanceHelix( yIn, Bfld_endpoint, h, yTemp2);
65
66  // we take the average
67  for( i = 0; i < nvar; i++ )
68  yOut[i] = 0.5 * ( yTemp[i] + yTemp2[i] );
69
70  // NormaliseTangentVector( yOut );
71 }
void DumbStepper(const G4double y[], G4ThreeVector Bfld, G4double h, G4double yout[])
void AdvanceHelix(const G4double yIn[], G4ThreeVector Bfld, G4double h, G4double yHelix[], G4double yHelix2[]=0)
double G4double
Definition: G4Types.hh:76
int G4int
Definition: G4Types.hh:78
void MagFieldEvaluate(const G4double y[], G4ThreeVector &Bfield)