[1197] | 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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[1340] | 26 | // $Id: G4Pow.hh,v 1.7 2010/08/24 08:12:08 gcosmo Exp $ |
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| 27 | // GEANT4 tag $Name: global-V09-03-22 $ |
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[1197] | 28 | // |
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| 29 | // |
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| 30 | // ------------------------------------------------------------------- |
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| 31 | // |
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| 32 | // Class G4Pow |
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| 33 | // |
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| 34 | // Class description: |
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| 35 | // |
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| 36 | // Utility singleton class for the fast computation of log and pow |
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[1315] | 37 | // functions. Integer argument should in the interval 0-255, no |
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| 38 | // check is performed inside these methods for performance reasons. |
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| 39 | // Computations with double arguments are fast for the interval |
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| 40 | // 0.5-255.5, standard library is used in the opposite case |
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[1197] | 41 | |
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| 42 | // Author: Vladimir Ivanchenko |
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| 43 | // |
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| 44 | // Creation date: 23.05.2009 |
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| 45 | // ------------------------------------------------------------------- |
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| 46 | |
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| 47 | #ifndef G4Pow_h |
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| 48 | #define G4Pow_h 1 |
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| 49 | |
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| 50 | #include "globals.hh" |
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| 51 | #include "G4DataVector.hh" |
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| 52 | |
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| 53 | class G4Pow |
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| 54 | { |
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| 55 | |
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| 56 | public: |
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| 57 | |
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| 58 | static G4Pow* GetInstance(); |
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| 59 | |
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| 60 | // Fast computation of Z^1/3 |
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| 61 | // |
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| 62 | inline G4double Z13(G4int Z); |
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| 63 | inline G4double A13(G4double A); |
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| 64 | |
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| 65 | // Fast computation of Z^2/3 |
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| 66 | // |
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| 67 | inline G4double Z23(G4int Z); |
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| 68 | inline G4double A23(G4double A); |
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| 69 | |
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| 70 | // Fast computation of log(Z) |
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| 71 | // |
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| 72 | inline G4double logZ(G4int Z); |
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| 73 | inline G4double logA(G4double A); |
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| 74 | |
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| 75 | // Fast computation of log10(Z) |
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| 76 | // |
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| 77 | inline G4double log10Z(G4int Z); |
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| 78 | inline G4double log10A(G4double A); |
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| 79 | |
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| 80 | // Fast computation of pow(Z,X) |
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| 81 | // |
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| 82 | inline G4double powZ(G4int Z, G4double y); |
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| 83 | inline G4double powA(G4double A, G4double y); |
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[1340] | 84 | G4double powN(G4double x, G4int n); |
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[1197] | 85 | |
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| 86 | // Fast factorial |
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| 87 | // |
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| 88 | inline G4double factorial(G4int Z); |
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[1340] | 89 | inline G4double logfactorial(G4int Z); |
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[1197] | 90 | |
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| 91 | private: |
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| 92 | |
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| 93 | G4Pow(); |
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| 94 | ~G4Pow(); |
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| 95 | |
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| 96 | private: |
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| 97 | |
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| 98 | static G4Pow* fInstance; |
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| 99 | |
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| 100 | G4double onethird; |
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| 101 | |
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| 102 | G4DataVector pz13; |
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| 103 | G4DataVector lz; |
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| 104 | G4DataVector fact; |
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[1340] | 105 | G4DataVector logfact; |
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[1197] | 106 | }; |
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| 107 | |
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| 108 | // ------------------------------------------------------------------- |
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| 109 | |
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| 110 | inline G4double G4Pow::Z13(G4int Z) |
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| 111 | { |
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| 112 | return pz13[Z]; |
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| 113 | } |
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| 114 | |
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| 115 | inline G4double G4Pow::A13(G4double A) |
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| 116 | { |
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[1315] | 117 | const G4double minA = 0.5000001; |
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| 118 | const G4double maxA = 255.5; |
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[1197] | 119 | |
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| 120 | G4double res; |
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[1315] | 121 | if((A >= minA) && (A <= maxA)) |
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[1197] | 122 | { |
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[1315] | 123 | G4int i = G4int(A + 0.5); |
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[1197] | 124 | G4double x = (1.0 - A/G4double(i))*onethird; |
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| 125 | res = pz13[i]*(1.0 + x - x*x*(1.0 - 1.66666666*x)); |
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| 126 | } |
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| 127 | else |
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| 128 | { |
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| 129 | res = std::pow(A, onethird); |
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| 130 | } |
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| 131 | return res; |
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| 132 | } |
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| 133 | |
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| 134 | inline G4double G4Pow::Z23(G4int Z) |
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| 135 | { |
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| 136 | G4double x = Z13(Z); |
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| 137 | return x*x; |
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| 138 | } |
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| 139 | |
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| 140 | inline G4double G4Pow::A23(G4double A) |
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| 141 | { |
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| 142 | G4double x = A13(A); |
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| 143 | return x*x; |
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| 144 | } |
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| 145 | |
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| 146 | inline G4double G4Pow::logZ(G4int Z) |
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| 147 | { |
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| 148 | return lz[Z]; |
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| 149 | } |
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| 150 | |
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| 151 | inline G4double G4Pow::logA(G4double A) |
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| 152 | { |
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[1315] | 153 | const G4double minA = 0.5000001; |
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| 154 | const G4double maxA = 255.5; |
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[1197] | 155 | |
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| 156 | G4double res; |
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[1315] | 157 | if((A >= minA) && (A <= maxA)) |
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[1197] | 158 | { |
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[1315] | 159 | G4int i = G4int(A + 0.5); |
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[1197] | 160 | G4double x = 1.0 - A/G4double(i); |
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| 161 | res = lz[i] + x*(1.0 - 0.5*x + onethird*x*x); |
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| 162 | } |
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| 163 | else |
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| 164 | { |
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| 165 | res = std::log(A); |
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| 166 | } |
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| 167 | return res; |
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| 168 | } |
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| 169 | |
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| 170 | inline G4double G4Pow::log10Z(G4int Z) |
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| 171 | { |
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| 172 | return lz[Z]/lz[10]; |
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| 173 | } |
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| 174 | |
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| 175 | inline G4double G4Pow::log10A(G4double A) |
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| 176 | { |
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| 177 | return logA(A)/lz[10]; |
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| 178 | } |
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| 179 | |
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| 180 | inline G4double G4Pow::powZ(G4int Z, G4double y) |
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| 181 | { |
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| 182 | return std::exp(y*lz[Z]); |
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| 183 | } |
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| 184 | |
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| 185 | inline G4double G4Pow::powA(G4double A, G4double y) |
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| 186 | { |
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| 187 | return std::exp(y*logA(A)); |
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| 188 | } |
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| 189 | |
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| 190 | inline G4double G4Pow::factorial(G4int Z) |
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| 191 | { |
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| 192 | return fact[Z]; |
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| 193 | } |
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| 194 | |
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[1340] | 195 | inline G4double G4Pow::logfactorial(G4int Z) |
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| 196 | { |
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| 197 | return logfact[Z]; |
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| 198 | } |
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| 199 | |
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[1197] | 200 | // ------------------------------------------------------------------- |
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| 201 | |
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| 202 | #endif |
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| 203 | |
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