1 | // |
---|
2 | // ******************************************************************** |
---|
3 | // * License and Disclaimer * |
---|
4 | // * * |
---|
5 | // * The Geant4 software is copyright of the Copyright Holders of * |
---|
6 | // * the Geant4 Collaboration. It is provided under the terms and * |
---|
7 | // * conditions of the Geant4 Software License, included in the file * |
---|
8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
---|
9 | // * include a list of copyright holders. * |
---|
10 | // * * |
---|
11 | // * Neither the authors of this software system, nor their employing * |
---|
12 | // * institutes,nor the agencies providing financial support for this * |
---|
13 | // * work make any representation or warranty, express or implied, * |
---|
14 | // * regarding this software system or assume any liability for its * |
---|
15 | // * use. Please see the license in the file LICENSE and URL above * |
---|
16 | // * for the full disclaimer and the limitation of liability. * |
---|
17 | // * * |
---|
18 | // * This code implementation is the result of the scientific and * |
---|
19 | // * technical work of the GEANT4 collaboration. * |
---|
20 | // * By using, copying, modifying or distributing the software (or * |
---|
21 | // * any work based on the software) you agree to acknowledge its * |
---|
22 | // * use in resulting scientific publications, and indicate your * |
---|
23 | // * acceptance of all terms of the Geant4 Software license. * |
---|
24 | // ******************************************************************** |
---|
25 | // |
---|
26 | // |
---|
27 | // $Id: G4HelixExplicitEuler.cc,v 1.8 2007/12/10 16:29:49 gunter Exp $ |
---|
28 | // GEANT4 tag $Name: geant4-09-02-cand-01 $ |
---|
29 | // |
---|
30 | // |
---|
31 | // Helix Explicit Euler: x_1 = x_0 + helix(h) |
---|
32 | // with helix(h) being a helix piece of length h |
---|
33 | // most simple approach for solving linear differential equations. |
---|
34 | // Take the current derivative and add it to the current position. |
---|
35 | // |
---|
36 | // W.Wander <wwc@mit.edu> 12/09/97 |
---|
37 | // ------------------------------------------------------------------- |
---|
38 | |
---|
39 | #include "G4HelixExplicitEuler.hh" |
---|
40 | #include "G4ThreeVector.hh" |
---|
41 | |
---|
42 | |
---|
43 | void G4HelixExplicitEuler::Stepper( const G4double yInput[7], |
---|
44 | const G4double*, |
---|
45 | G4double Step, |
---|
46 | G4double yOut[7], |
---|
47 | G4double yErr[]) |
---|
48 | |
---|
49 | { |
---|
50 | |
---|
51 | //Estimation of the Stepping Angle |
---|
52 | |
---|
53 | G4ThreeVector Bfld; |
---|
54 | MagFieldEvaluate(yInput, Bfld); |
---|
55 | |
---|
56 | const G4int nvar = 6 ; |
---|
57 | G4int i; |
---|
58 | G4double yTemp[7], yIn[7] ; |
---|
59 | G4ThreeVector Bfld_midpoint; |
---|
60 | // Saving yInput because yInput and yOut can be aliases for same array |
---|
61 | for(i=0;i<nvar;i++) yIn[i]=yInput[i]; |
---|
62 | |
---|
63 | G4double h = Step * 0.5; |
---|
64 | |
---|
65 | // Do full step and two half steps |
---|
66 | G4double yTemp2[7]; |
---|
67 | AdvanceHelix(yIn, Bfld, h, yTemp2,yTemp); |
---|
68 | MagFieldEvaluate(yTemp2, Bfld_midpoint) ; |
---|
69 | AdvanceHelix(yTemp2, Bfld_midpoint, h, yOut); |
---|
70 | |
---|
71 | // Error estimation |
---|
72 | for(i=0;i<nvar;i++) { |
---|
73 | yErr[i] = yOut[i] - yTemp[i] ; |
---|
74 | } |
---|
75 | |
---|
76 | } |
---|
77 | |
---|
78 | G4double G4HelixExplicitEuler::DistChord() const |
---|
79 | { |
---|
80 | // Implementation : must check whether h/R > 2 pi !! |
---|
81 | // If( h/R < pi) use G4LineSection::DistLine |
---|
82 | // Else DistChord=R_helix |
---|
83 | // |
---|
84 | G4double distChord; |
---|
85 | G4double Ang_curve=GetAngCurve(); |
---|
86 | |
---|
87 | |
---|
88 | if(Ang_curve<=pi){ |
---|
89 | distChord=GetRadHelix()*(1-std::cos(0.5*Ang_curve)); |
---|
90 | } |
---|
91 | else |
---|
92 | if(Ang_curve<twopi){ |
---|
93 | distChord=GetRadHelix()*(1+std::cos(0.5*(twopi-Ang_curve))); |
---|
94 | } |
---|
95 | else{ |
---|
96 | distChord=2.*GetRadHelix(); |
---|
97 | } |
---|
98 | |
---|
99 | return distChord; |
---|
100 | |
---|
101 | } |
---|
102 | void |
---|
103 | G4HelixExplicitEuler::DumbStepper( const G4double yIn[], |
---|
104 | G4ThreeVector Bfld, |
---|
105 | G4double h, |
---|
106 | G4double yOut[]) |
---|
107 | { |
---|
108 | |
---|
109 | AdvanceHelix(yIn, Bfld, h, yOut); |
---|
110 | |
---|
111 | } |
---|