| Geant4 Cross Reference |
1 // 1
2 // *******************************************
3 // * License and Disclaimer
4 // *
5 // * The Geant4 software is copyright of th
6 // * the Geant4 Collaboration. It is provided
7 // * conditions of the Geant4 Software License
8 // * LICENSE and available at http://cern.ch/
9 // * include a list of copyright holders.
10 // *
11 // * Neither the authors of this software syst
12 // * institutes,nor the agencies providing fin
13 // * work make any representation or warran
14 // * regarding this software system or assum
15 // * use. Please see the license in the file
16 // * for the full disclaimer and the limitatio
17 // *
18 // * This code implementation is the result
19 // * technical work of the GEANT4 collaboratio
20 // * By using, copying, modifying or distri
21 // * any work based on the software) you ag
22 // * use in resulting scientific publicati
23 // * acceptance of all terms of the Geant4 Sof
24 // *******************************************
25 //
26 //
27 //
28 //
29 // -------------------------------------------
30 // GEANT 4 class header file
31 // -------------------------------------------
32 // Class description:
33 //
34 // Function returning a unit 3-vector homogene
35 // solid angle. It can be used in any particle
36 // instead of:
37 // z=R1, x=SQRT(1-R1*R1)*SIN(2*pi*R2), y=SQR
38 // providing more performant results.
39
40 // History:
41 // 19.10.17 E. Tcherniaev, use of G.Marsagl
42 // 06.04.17 E. Tcherniaev, added G4RandomDi
43 // 15.03.16 E. Tcherniaev, removed unnecess
44 // 18.03.08 V. Grichine, unit radius sphere
45 // ~ 2007 M. Kossov, algorithm based on 8
46 //
47 // -------------------------------------------
48 #ifndef G4RANDOMDIR_HH
49 #define G4RANDOMDIR_HH
50
51 #include <CLHEP/Units/PhysicalConstants.h>
52
53 #include "G4ThreeVector.hh"
54 #include "Randomize.hh"
55 #include "globals.hh"
56
57 // G.Marsaglia (1972) method
58 inline G4ThreeVector G4RandomDirection()
59 {
60 G4double u, v, b;
61 do
62 {
63 u = 2. * G4UniformRand() - 1.;
64 v = 2. * G4UniformRand() - 1.;
65 b = u * u + v * v;
66 } while(b > 1.);
67 G4double a = 2. * std::sqrt(1. - b);
68 return G4ThreeVector(a * u, a * v, 2. * b -
69 }
70
71 inline G4ThreeVector G4RandomDirection(G4doubl
72 {
73 G4double z = (1. - cosTheta) * G4UniformRa
74 G4double rho = std::sqrt((1. + z) * (1. - z)
75 G4double phi = CLHEP::twopi * G4UniformRand(
76 return G4ThreeVector(rho * std::cos(phi), rh
77 }
78
79 #endif /* G4RANDOMDIR_HH */
80