| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These *
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| 9 | // * include a list of copyright holders. *
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| 10 | // * *
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| 11 | // * Neither the authors of this software system, nor their employing *
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| 12 | // * institutes,nor the agencies providing financial support for this *
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| 13 | // * work make any representation or warranty, express or implied, *
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| 14 | // * regarding this software system or assume any liability for its *
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| 15 | // * use. Please see the license in the file LICENSE and URL above *
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| 16 | // * for the full disclaimer and the limitation of liability. *
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| 17 | // * *
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| 18 | // * This code implementation is the result of the scientific and *
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| 19 | // * technical work of the GEANT4 collaboration. *
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| 20 | // * By using, copying, modifying or distributing the software (or *
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| 21 | // * any work based on the software) you agree to acknowledge its *
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| 22 | // * use in resulting scientific publications, and indicate your *
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| 23 | // * acceptance of all terms of the Geant4 Software license. *
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| 24 | // ********************************************************************
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| 25 | //
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| 26 | // $Id: G4Pow.cc,v 1.4 2010/08/24 08:12:08 gcosmo Exp $
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| 27 | // GEANT4 tag $Name: global-V09-03-22 $
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| 28 | //
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| 29 | // -------------------------------------------------------------------
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| 30 | //
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| 31 | // GEANT4 Class file
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| 32 | //
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| 33 | //
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| 34 | // File name: G4Pow
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| 35 | //
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| 36 | // Author: Vladimir Ivanchenko
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| 37 | //
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| 38 | // Creation date: 23.05.2009
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| 39 | //
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| 40 | // -------------------------------------------------------------------
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| 41 |
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| 42 | #include "G4Pow.hh"
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| 43 |
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| 44 | G4Pow* G4Pow::fInstance = 0;
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| 45 |
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| 46 | // -------------------------------------------------------------------
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| 47 |
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| 48 | G4Pow* G4Pow::GetInstance()
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| 49 | {
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| 50 | if (fInstance == 0)
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| 51 | {
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| 52 | static G4Pow manager;
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| 53 | fInstance = &manager;
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| 54 | }
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| 55 | return fInstance;
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| 56 | }
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| 57 |
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| 58 | // -------------------------------------------------------------------
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| 59 |
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| 60 | G4Pow::G4Pow()
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| 61 | {
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| 62 | const G4int maxZ = 256;
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| 63 |
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| 64 | pz13.resize(maxZ,0.0);
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| 65 | lz.resize(maxZ,0.0);
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| 66 | fact.resize(maxZ,0.0);
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| 67 | logfact.resize(maxZ,0.0);
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| 68 |
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| 69 | onethird = 1.0/3.0;
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| 70 | G4double f = 1.0;
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| 71 |
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| 72 | for(G4int i=1; i<maxZ; ++i)
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| 73 | {
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| 74 | G4double x = G4double(i);
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| 75 | pz13[i] = std::pow(x,onethird);
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| 76 | lz[i] = std::log(x);
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| 77 | f *= x;
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| 78 | fact[i] = f;
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| 79 | logfact[i] = std::log(f);
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| 80 | }
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| 81 | fact[0] = 1.0;
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| 82 | logfact[0] = 0.0;
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| 83 | }
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| 84 |
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| 85 | // -------------------------------------------------------------------
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| 86 |
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| 87 | G4Pow::~G4Pow()
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| 88 | {}
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| 89 |
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| 90 | // -------------------------------------------------------------------
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| 91 |
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| 92 | G4double G4Pow::powN(G4double x, G4int n)
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| 93 | {
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| 94 | G4double res = 1.0;
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| 95 | if(n >= 0) { for(G4int i=0; i<n; ++i) { res *= x; } }
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| 96 | else if((n < 0) && (x != 0.0))
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| 97 | {
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| 98 | G4double y = 1.0/x;
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| 99 | G4int nn = -n;
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| 100 | for(G4int i=0; i<nn; ++i) { res *= y; }
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| 101 | }
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| 102 | return res;
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| 103 | }
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