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7cdba479 | 1 | /************************************************************************** |
2 | * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * | |
3 | * * | |
4 | * Author: The ALICE Off-line Project. * | |
5 | * Contributors are mentioned in the code where appropriate. * | |
6 | * * | |
7 | * Permission to use, copy, modify and distribute this software and its * | |
8 | * documentation strictly for non-commercial purposes is hereby granted * | |
9 | * without fee, provided that the above copyright notice appears in all * | |
10 | * copies and that both the copyright notice and this permission notice * | |
11 | * appear in the supporting documentation. The authors make no claims * | |
12 | * about the suitability of this software for any purpose. It is * | |
13 | * provided "as is" without express or implied warranty. * | |
14 | **************************************************************************/ | |
15 | ||
16 | /* $Id$ */ | |
17 | ||
18 | //----------------------------------------------------------------------------- | |
19 | // Class: AliPythiaRndm | |
cef490e6 | 20 | // Responsibilities: Interface to Root random number generator |
21 | // from Fortran (re-implements FINCTION PYR from PYTHIA) | |
22 | // Very similar to AliHijingRndm | |
23 | // Collaborators: AliPythia and AliGenPythia classes | |
24 | // Example: | |
25 | // | |
26 | // root> AliPythia::Instance(); | |
27 | // root> AliPythiaRndm::SetPythiaRandom(new TRandom3()); | |
28 | // root> AliPythiaRndm::GetPythiaRandom()->SetSeed(0); | |
29 | // root> cout<<"Seed "<< AliPythiaRndm::GetPythiaRandom()->GetSeed() <<endl; | |
30 | // | |
7cdba479 | 31 | //----------------------------------------------------------------------------- |
32 | ||
090026bf | 33 | #include <TMath.h> |
cef490e6 | 34 | #include <TRandom.h> |
7cdba479 | 35 | |
36 | #include "AliPythiaRndm.h" | |
37 | ||
38 | TRandom * AliPythiaRndm::fgPythiaRandom=0; | |
39 | ||
40 | ClassImp(AliPythiaRndm) | |
41 | ||
7cdba479 | 42 | |
43 | //_______________________________________________________________________ | |
44 | void AliPythiaRndm::SetPythiaRandom(TRandom *ran) { | |
45 | // | |
46 | // Sets the pointer to an existing random numbers generator | |
47 | // | |
48 | if(ran) fgPythiaRandom=ran; | |
49 | else fgPythiaRandom=gRandom; | |
50 | } | |
51 | ||
52 | //_______________________________________________________________________ | |
53 | TRandom * AliPythiaRndm::GetPythiaRandom() { | |
54 | // | |
55 | // Retrieves the pointer to the random numbers generator | |
56 | // | |
3cdd391f | 57 | if (!fgPythiaRandom) fgPythiaRandom=gRandom; |
7cdba479 | 58 | return fgPythiaRandom; |
59 | } | |
60 | ||
61 | //_______________________________________________________________________ | |
6889dd2d | 62 | #define pyr pyr_ |
63 | #define pygauss pygauss_ | |
64 | #define pyrset pyrset_ | |
65 | #define pyrget pyrget_ | |
7cdba479 | 66 | |
67 | extern "C" { | |
6889dd2d | 68 | Double_t pyr(Int_t*) |
69 | { | |
eb4da7a7 | 70 | // Wrapper to FUNCTION PYR from PYTHIA |
6889dd2d | 71 | // Uses static method to retrieve the pointer to the (C++) generator |
72 | Double_t r; | |
73 | do r=AliPythiaRndm::GetPythiaRandom()->Rndm(); | |
74 | while(0 >= r || r >= 1); | |
75 | return r; | |
76 | } | |
77 | ||
78 | Double_t pygauss(Double_t x0, Double_t sig) | |
79 | { | |
80 | Double_t s = 2.; | |
81 | Double_t v1 = 0.; | |
82 | Double_t v2 = 0.; | |
83 | ||
84 | while (s > 1.) { | |
85 | v1 = 2. * pyr(0) - 1.; | |
86 | v2 = 2. * pyr(0) - 1.; | |
87 | s = v1 * v1 + v2 * v2; | |
88 | } | |
89 | return v1 * TMath::Sqrt(-2. * TMath::Log(s) / s) * sig + x0; | |
90 | } | |
91 | ||
92 | void pyrset(Int_t*,Int_t*) {} | |
93 | void pyrget(Int_t*,Int_t*) {} | |
7cdba479 | 94 | } |