| 02626a96 |
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: AliPythiaRndm.cxx 34124 2009-08-06 09:32:43Z hristov $ */ |
| 17 | |
| 18 | //----------------------------------------------------------------------------- |
| 19 | // Class: AliPythiaRndm |
| 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 | // |
| 31 | //----------------------------------------------------------------------------- |
| 32 | |
| 33 | #include <TMath.h> |
| 34 | #include <TRandom.h> |
| 35 | |
| 36 | #include "AliPythiaRndm.h" |
| 37 | |
| 38 | TRandom * AliPythiaRndm::fgPythiaRandom=0; |
| 39 | |
| 40 | ClassImp(AliPythiaRndm) |
| 41 | |
| 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 | // |
| 57 | if (!fgPythiaRandom) fgPythiaRandom=gRandom; |
| 58 | return fgPythiaRandom; |
| 59 | } |
| 60 | |
| 61 | //_______________________________________________________________________ |
| 62 | #define pyr pyr_ |
| 63 | #define pygauss pygauss_ |
| 64 | #define pyrset pyrset_ |
| 65 | #define pyrget pyrget_ |
| 66 | |
| 67 | extern "C" { |
| 68 | Double_t pyr(Int_t*) |
| 69 | { |
| 70 | // Wrapper to FUNCTION PYR from PYTHIA |
| 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*) {} |
| 94 | } |
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