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25 // 22 //
26 // G4GaussChebyshevQ class implementation <<
27 // 23 //
28 // Author: V.Grichine, 13.05.1997 << 24 // $Id: G4GaussChebyshevQ.cc,v 1.3 2001/07/11 10:00:41 gunter Exp $
29 // ------------------------------------------- << 25 // GEANT4 tag $Name: geant4-06-00 $
30 << 26 //
31 #include "G4GaussChebyshevQ.hh" 27 #include "G4GaussChebyshevQ.hh"
32 #include "G4PhysicalConstants.hh" <<
33 28
34 // ------------------------------------------- 29 // -----------------------------------------------------
35 // 30 //
36 // Constructor for Gauss-Chebyshev quadrature 31 // Constructor for Gauss-Chebyshev quadrature method
>> 32
>> 33 G4GaussChebyshevQ::G4GaussChebyshevQ( function pFunction ,
>> 34 G4int nChebyshev )
>> 35 : G4VGaussianQuadrature(pFunction)
>> 36 {
>> 37 G4int i ;
>> 38 fNumber = nChebyshev ; // Try to reduce fNumber twice ??
>> 39 G4double cof = pi/fNumber ;
>> 40 fAbscissa = new G4double[fNumber] ;
>> 41 fWeight = new G4double[fNumber] ;
>> 42 for(i=0;i<fNumber;i++)
>> 43 {
>> 44 fAbscissa[i] = cos(cof*(i + 0.5)) ;
>> 45 fWeight[i] = cof*sqrt(1 - fAbscissa[i]*fAbscissa[i]) ;
>> 46 }
>> 47 }
>> 48
>> 49 // ----------------------------------------------------------------------
37 // 50 //
38 G4GaussChebyshevQ::G4GaussChebyshevQ(function << 51
39 : G4VGaussianQuadrature(pFunction) << 52 G4GaussChebyshevQ::~G4GaussChebyshevQ()
40 { 53 {
41 fNumber = nChebyshev; // Try to reduce << 54 ;
42 G4double cof = pi / fNumber; <<
43 fAbscissa = new G4double[fNumber]; <<
44 fWeight = new G4double[fNumber]; <<
45 for(G4int i = 0; i < fNumber; ++i) <<
46 { <<
47 fAbscissa[i] = std::cos(cof * (i + 0.5)); <<
48 fWeight[i] = cof * std::sqrt(1 - fAbscis <<
49 } <<
50 } 55 }
51 56
52 // ------------------------------------------- 57 // -------------------------------------------------------------------------------
53 // 58 //
54 // Integrates function pointed by fFunction fr << 59 // Integrates function pointed by fFunction from a to b by Gauss-Chebyshev
55 // quadrature method 60 // quadrature method
56 // <<
57 G4double G4GaussChebyshevQ::Integral(G4double <<
58 { <<
59 G4double xDiff = 0.5 * (b - a), xMean = 0.5 <<
60 integral = 0.0; <<
61 61
62 for(G4int i = 0; i < fNumber; ++i) << 62 G4double
63 { << 63 G4GaussChebyshevQ::Integral(G4double a, G4double b) const
64 dx = xDiff * fAbscissa[i]; << 64 {
65 integral += fWeight[i] * fFunction(xMean + << 65 G4int i ;
66 } << 66 G4double xDiff, xMean, dx, integral = 0.0 ;
67 return integral *= xDiff; << 67
>> 68 xMean = 0.5*(a + b) ;
>> 69 xDiff = 0.5*(b - a) ;
>> 70 for(i=0;i<fNumber;i++)
>> 71 {
>> 72 dx = xDiff*fAbscissa[i] ;
>> 73 integral += fWeight[i]*fFunction(xMean + dx) ;
>> 74 }
>> 75 return integral *= xDiff ;
68 } 76 }
69 77