Geant4  10.03
G4VGaussianQuadrature.cc
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27 // $Id: G4VGaussianQuadrature.cc 69546 2013-05-08 09:50:34Z gcosmo $
28 //
29 // Implementation file for G4VGaussianQuadrature virtual base class
30 //
31 
32 #include "G4ios.hh"
33 #include "globals.hh"
34 #include "G4VGaussianQuadrature.hh"
35 
37  : fFunction(pFunction), fAbscissa(0), fWeight(0), fNumber(0)
38 {
39 }
40 
41 // -------------------------------------------------------------------
42 //
43 // Virtual destructor which deletes dynamically allocated memory
44 //
45 
47 {
48  delete[] fAbscissa ;
49  delete[] fWeight ;
50 }
51 
52 // -------------------------- Access functions ----------------------------------
53 
56 {
57  return fAbscissa[index] ;
58 }
59 
62 {
63  return fWeight[index] ;
64 }
65 
67 {
68  return fNumber ;
69 }
70 
71 // ----------------------------------------------------------------------------
72 //
73 // Auxiliary function which returns the value of std::log(gamma-function(x))
74 //
75 
76 G4double
78 {
79 
80 // Returns the value ln(Gamma(xx) for xx > 0. Full accuracy is obtained for
81 // xx > 1. For 0 < xx < 1. the reflection formula (6.1.4) can be used first.
82 // (Adapted from Numerical Recipes in C)
83 
84  static const G4double cof[6] = { 76.18009172947146, -86.50532032941677,
85  24.01409824083091, -1.231739572450155,
86  0.1208650973866179e-2, -0.5395239384953e-5 };
87  G4double x = xx - 1.0;
88  G4double tmp = x + 5.5;
89  tmp -= (x + 0.5) * std::log(tmp);
90  G4double ser = 1.000000000190015;
91 
92  for ( size_t j = 0; j <= 5; j++ )
93  {
94  x += 1.0;
95  ser += cof[j]/x;
96  }
97  return -tmp + std::log(2.5066282746310005*ser);
98 }
G4double GetWeight(G4int index) const
G4VGaussianQuadrature(function pFunction)
int G4int
Definition: G4Types.hh:78
G4double GetAbscissa(G4int index) const
G4double GammaLogarithm(G4double xx)
double G4double
Definition: G4Types.hh:76