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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 // G4Pow 27 // 28 // Class description: 29 // 30 // Utility singleton class for the fast comput 31 // functions. Integer argument should be in th 32 // check is performed inside these methods for 33 // For factorial integer argument should be in 34 // Computations with double arguments are fast 35 // 0.002-511.5 for all functions except expone 36 // for the interval 0-84.4, standard library i 37 38 // Author: Vladimir Ivanchenko, 23.05.2009 39 // ------------------------------------------- 40 #ifndef G4Pow_hh 41 #define G4Pow_hh 1 42 43 #include "G4DataVector.hh" 44 #include "G4Exp.hh" 45 #include "G4Log.hh" 46 #include "globals.hh" 47 48 class G4Pow 49 { 50 public: 51 static G4Pow* GetInstance(); 52 ~G4Pow() = default; 53 54 // Fast computation of Z^1/3 55 // 56 inline G4double Z13(G4int Z) const; 57 G4double A13(G4double A) const; 58 59 // Fast computation of Z^2/3 60 // 61 inline G4double Z23(G4int Z) const; 62 inline G4double A23(G4double A) const; 63 64 // Fast computation of log(Z) 65 // 66 inline G4double logZ(G4int Z) const; 67 inline G4double logA(G4double A) const; 68 inline G4double logX(G4double x) const; 69 70 // Fast computation of log10(Z) 71 // 72 inline G4double log10Z(G4int Z) const; 73 inline G4double log10A(G4double A) const; 74 75 // Fast computation of exp(X) 76 // 77 inline G4double expA(G4double A) const; 78 79 // Fast computation of pow(Z,X) 80 // 81 inline G4double powZ(G4int Z, G4double y) co 82 inline G4double powA(G4double A, G4double y) 83 G4double powN(G4double x, G4int n) const; 84 85 // Fast factorial 86 // 87 inline G4double factorial(G4int Z) const; 88 inline G4double logfactorial(G4int Z) const; 89 90 private: 91 G4Pow(); 92 93 G4double A13Low(const G4double, const G4bool 94 G4double A13High(const G4double, const G4boo 95 96 inline G4double logBase(G4double x) const; 97 98 static G4Pow* fpInstance; 99 100 const G4double onethird = 1.0 / 3.0; 101 const G4int max2 = 5; 102 103 G4double maxA; 104 G4double maxLowA; 105 G4double maxA2; 106 G4double maxAexp; 107 108 G4DataVector ener; 109 G4DataVector logen; 110 G4DataVector pz13; 111 G4DataVector lowa13; 112 G4DataVector lz; 113 G4DataVector lz2; 114 G4DataVector fexp; 115 G4DataVector fact; 116 G4DataVector logfact; 117 }; 118 119 // ----------------------------- 120 // Inline methods implementation 121 // ----------------------------- 122 123 inline G4double G4Pow::Z13(G4int Z) const { re 124 125 inline G4double G4Pow::Z23(G4int Z) const 126 { 127 G4double x = Z13(Z); 128 return x * x; 129 } 130 131 inline G4double G4Pow::A23(G4double A) const 132 { 133 G4double x = A13(A); 134 return x * x; 135 } 136 137 inline G4double G4Pow::logZ(G4int Z) const { r 138 139 inline G4double G4Pow::logBase(G4double a) con 140 { 141 G4double res; 142 if(a <= maxA2) 143 { 144 G4int i = G4int(max2 * (a - 1) + 0.5); 145 if(i > max2) 146 { 147 i = max2; 148 } 149 G4double x = a / (G4double(i) / max2 + 1) 150 res = lz2[i] + x * (1.0 - (0.5 - on 151 } 152 else if(a <= maxA) 153 { 154 G4int i = G4int(a + 0.5); 155 G4double x = a / G4double(i) - 1; 156 res = lz[i] + x * (1.0 - (0.5 - one 157 } 158 else 159 { 160 res = G4Log(a); 161 } 162 return res; 163 } 164 165 inline G4double G4Pow::logA(G4double A) const 166 { 167 return (1.0 <= A ? logBase(A) : -logBase(1. 168 } 169 170 inline G4double G4Pow::logX(G4double x) const 171 { 172 G4double res = 0.0; 173 G4double a = (1.0 <= x) ? x : 1.0 / x; 174 175 if(a <= maxA) 176 { 177 res = logBase(a); 178 } 179 else if(a <= ener[2]) 180 { 181 res = logen[1] + logBase(a / ener[1]); 182 } 183 else if(a <= ener[3]) 184 { 185 res = logen[2] + logBase(a / ener[2]); 186 } 187 else 188 { 189 res = G4Log(a); 190 } 191 192 if(1.0 > x) 193 { 194 res = -res; 195 } 196 return res; 197 } 198 199 inline G4double G4Pow::log10Z(G4int Z) const { 200 201 inline G4double G4Pow::log10A(G4double A) cons 202 203 inline G4double G4Pow::expA(G4double A) const 204 { 205 G4double res; 206 G4double a = (0.0 <= A) ? A : -A; 207 208 if(a <= maxAexp) 209 { 210 G4int i = G4int(2 * a + 0.5); 211 G4double x = a - i * 0.5; 212 res = fexp[i] * (1.0 + x * (1.0 + 0 213 } 214 else 215 { 216 res = G4Exp(a); 217 } 218 if(0.0 > A) 219 { 220 res = 1.0 / res; 221 } 222 return res; 223 } 224 225 inline G4double G4Pow::powZ(G4int Z, G4double 226 { 227 return expA(y * lz[Z]); 228 } 229 230 inline G4double G4Pow::powA(G4double A, G4doub 231 { 232 return (0.0 == A ? 0.0 : expA(y * logX(A))); 233 } 234 235 inline G4double G4Pow::factorial(G4int Z) cons 236 237 inline G4double G4Pow::logfactorial(G4int Z) c 238 239 #endif 240