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>> 1 // This code implementation is the intellectual property of
>> 2 // the GEANT4 collaboration.
1 // 3 //
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15 // * use. Please see the license in the file <<
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17 // * <<
18 // * This code implementation is the result <<
19 // * technical work of the GEANT4 collaboratio <<
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21 // * any work based on the software) you ag <<
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24 // ******************************************* <<
25 // 7 //
26 // G4GaussChebyshevQ class implementation << 8 // $Id: G4GaussChebyshevQ.cc,v 1.2 1999/11/16 17:31:09 gcosmo Exp $
>> 9 // GEANT4 tag $Name: geant4-01-00 $
27 // 10 //
28 // Author: V.Grichine, 13.05.1997 <<
29 // ------------------------------------------- <<
30 <<
31 #include "G4GaussChebyshevQ.hh" 11 #include "G4GaussChebyshevQ.hh"
32 #include "G4PhysicalConstants.hh" <<
33 12
34 // ------------------------------------------- 13 // -----------------------------------------------------
35 // 14 //
36 // Constructor for Gauss-Chebyshev quadrature 15 // Constructor for Gauss-Chebyshev quadrature method
>> 16
>> 17 G4GaussChebyshevQ::G4GaussChebyshevQ( function pFunction ,
>> 18 G4int nChebyshev )
>> 19 : G4VGaussianQuadrature(pFunction)
>> 20 {
>> 21 G4int i ;
>> 22 fNumber = nChebyshev ; // Try to reduce fNumber twice ??
>> 23 G4double cof = pi/fNumber ;
>> 24 fAbscissa = new G4double[fNumber] ;
>> 25 fWeight = new G4double[fNumber] ;
>> 26 for(i=0;i<fNumber;i++)
>> 27 {
>> 28 fAbscissa[i] = cos(cof*(i + 0.5)) ;
>> 29 fWeight[i] = cof*sqrt(1 - fAbscissa[i]*fAbscissa[i]) ;
>> 30 }
>> 31 }
>> 32
>> 33 // ----------------------------------------------------------------------
37 // 34 //
38 G4GaussChebyshevQ::G4GaussChebyshevQ(function << 35
39 : G4VGaussianQuadrature(pFunction) << 36 G4GaussChebyshevQ::~G4GaussChebyshevQ()
40 { 37 {
41 fNumber = nChebyshev; // Try to reduce << 38 ;
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 } 39 }
51 40
52 // ------------------------------------------- 41 // -------------------------------------------------------------------------------
53 // 42 //
54 // Integrates function pointed by fFunction fr << 43 // Integrates function pointed by fFunction from a to b by Gauss-Chebyshev
55 // quadrature method 44 // quadrature method
56 // <<
57 G4double G4GaussChebyshevQ::Integral(G4double <<
58 { <<
59 G4double xDiff = 0.5 * (b - a), xMean = 0.5 <<
60 integral = 0.0; <<
61 45
62 for(G4int i = 0; i < fNumber; ++i) << 46 G4double
63 { << 47 G4GaussChebyshevQ::Integral(G4double a, G4double b) const
64 dx = xDiff * fAbscissa[i]; << 48 {
65 integral += fWeight[i] * fFunction(xMean + << 49 G4int i ;
66 } << 50 G4double xDiff, xMean, dx, integral = 0.0 ;
67 return integral *= xDiff; << 51
>> 52 xMean = 0.5*(a + b) ;
>> 53 xDiff = 0.5*(b - a) ;
>> 54 for(i=0;i<fNumber;i++)
>> 55 {
>> 56 dx = xDiff*fAbscissa[i] ;
>> 57 integral += fWeight[i]*fFunction(xMean + dx) ;
>> 58 }
>> 59 return integral *= xDiff ;
68 } 60 }
69 61