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G4ErrorMag_UsualEqRhs.cc
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27 // $Id: G4ErrorMag_UsualEqRhs.cc 69786 2013-05-15 09:38:51Z gcosmo $
28 //
29 //
30 // --------------------------------------------------------------------
31 // GEANT 4 class implementation file
32 // --------------------------------------------------------------------
33 
34 #include "G4ErrorMag_UsualEqRhs.hh"
35 #include "G4ErrorPropagatorData.hh"
36 
37 //---------------------------------------------------------------------
38 
40  : G4Mag_UsualEqRhs( MagField )
41 {
42 }
43 
45 {
46 }
47 
48 //---------------------------------------------------------------------
49 void
51  const G4double B[3],
52  G4double dydx[] ) const
53 {
54 
56 
59  {
60  G4double momentum_mag_square = sqr(y[3]) + sqr(y[4]) + sqr(y[5]);
61  G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
62 
63  G4double cof = FCof()*inv_momentum_magnitude;
64 
65  dydx[3] = cof*(y[4]*(-B[2]) - y[5]*(-B[1])) ;
66  dydx[4] = cof*(y[5]*(-B[0]) - y[3]*(-B[2])) ;
67  dydx[5] = cof*(y[3]*(-B[1]) - y[4]*(-B[0])) ;
68  }
69  return;
70 }