Geant4  10.02.p01
G4GaussChebyshevQ.cc
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27 // $Id: G4GaussChebyshevQ.cc 67970 2013-03-13 10:10:06Z gcosmo $
28 //
29 #include "G4GaussChebyshevQ.hh"
30 #include "G4PhysicalConstants.hh"
31 
32 // -----------------------------------------------------
33 //
34 // Constructor for Gauss-Chebyshev quadrature method
35 
37  G4int nChebyshev )
38  : G4VGaussianQuadrature(pFunction)
39 {
40  fNumber = nChebyshev ; // Try to reduce fNumber twice ??
41  G4double cof = pi/fNumber ;
42  fAbscissa = new G4double[fNumber] ;
43  fWeight = new G4double[fNumber] ;
44  for(G4int i=0;i<fNumber;i++)
45  {
46  fAbscissa[i] = std::cos(cof*(i + 0.5)) ;
47  fWeight[i] = cof*std::sqrt(1 - fAbscissa[i]*fAbscissa[i]) ;
48  }
49 }
50 
51 // ----------------------------------------------------------------------
52 //
53 
55 {
56 }
57 
58 // -------------------------------------------------------------------------------
59 //
60 // Integrates function pointed by fFunction from a to b by Gauss-Chebyshev
61 // quadrature method
62 
63 G4double
65 {
66  G4double xDiff=0.5*(b - a),
67  xMean=0.5*(a + b),
68  dx=0.0, integral=0.0 ;
69 
70  for(G4int i=0;i<fNumber;i++)
71  {
72  dx = xDiff*fAbscissa[i] ;
73  integral += fWeight[i]*fFunction(xMean + dx) ;
74  }
75  return integral *= xDiff ;
76 }
G4double a
Definition: TRTMaterials.hh:39
int G4int
Definition: G4Types.hh:78
G4GaussChebyshevQ(function pFunction, G4int nChebyshev)
static const double pi
Definition: G4SIunits.hh:74
G4double Integral(G4double a, G4double b) const
double G4double
Definition: G4Types.hh:76