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>> 1 // This code implementation is the intellectual property of >> 2 // the GEANT4 collaboration. 1 // 3 // 2 // ******************************************* << 4 // By copying, distributing or modifying the Program (or any work 3 // * License and Disclaimer << 5 // based on the Program) you indicate your acceptance of this statement, 4 // * << 6 // and all its terms. 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 // 7 // 26 // G4GaussLaguerreQ class implementation << 8 // $Id: G4GaussLaguerreQ.cc,v 1.3 2000/11/20 17:26:43 gcosmo Exp $ >> 9 // GEANT4 tag $Name: geant4-03-01 $ 27 // 10 // 28 // Author: V.Grichine, 13.05.1997 << 29 // ------------------------------------------- << 30 << 31 #include "G4GaussLaguerreQ.hh" 11 #include "G4GaussLaguerreQ.hh" 32 12 >> 13 >> 14 33 // ------------------------------------------- 15 // ------------------------------------------------------------ 34 // 16 // 35 // Constructor for Gauss-Laguerre quadrature m 17 // Constructor for Gauss-Laguerre quadrature method: integral from zero to 36 // infinity of std::pow(x,alpha)*std::exp(-x)* << 18 // infinity of pow(x,alpha)*exp(-x)*f(x). The value of nLaguerre sets the accuracy. 37 // The value of nLaguerre sets the accuracy. << 19 // The constructor creates arrays fAbscissa[0,..,nLaguerre-1] and 38 // The constructor creates arrays fAbscissa[0, << 20 // fWeight[0,..,nLaguerre-1] . 39 // fWeight[0,..,nLaguerre-1] . << 40 // 21 // 41 22 42 G4GaussLaguerreQ::G4GaussLaguerreQ(function pF << 23 G4GaussLaguerreQ::G4GaussLaguerreQ( function pFunction, 43 G4int nLagu << 24 G4double alpha, 44 : G4VGaussianQuadrature(pFunction) << 25 G4int nLaguerre ) >> 26 : G4VGaussianQuadrature(pFunction) 45 { 27 { 46 const G4double tolerance = 1.0e-10; << 28 const G4double tolerance = 1.0e-10 ; 47 const G4int maxNumber = 12; << 29 const G4int maxNumber = 12 ; 48 G4int i = 1, k = 1; << 30 G4int i, j, k ; 49 G4double newton0 = 0.0, newton1 = 0.0, temp1 << 31 G4double newton=0.; 50 temp = 0.0, cofi = 0.0; << 32 G4double newton1, temp1, temp2, temp3, temp, cofi ; 51 << 33 52 fNumber = nLaguerre; << 34 fNumber = nLaguerre ; 53 fAbscissa = new G4double[fNumber]; << 35 fAbscissa = new G4double[fNumber] ; 54 fWeight = new G4double[fNumber]; << 36 fWeight = new G4double[fNumber] ; 55 << 37 56 for(i = 1; i <= fNumber; ++i) // Loop over << 38 for(i=1;i<=fNumber;i++) // Loop over the desired roots 57 { << 39 { 58 if(i == 1) << 40 if(i == 1) 59 { << 41 { 60 newton0 = (1.0 + alpha) * (3.0 + 0.92 * << 42 newton = (1.0 + alpha)*(3.0 + 0.92*alpha)/(1.0 + 2.4*fNumber + 1.8*alpha) ; 61 (1.0 + 2.4 * fNumber + 1.8 * a << 43 } 62 } << 44 else if(i == 2) 63 else if(i == 2) << 45 { 64 { << 46 newton += (15.0 + 6.25*alpha)/(1.0 + 0.9*alpha + 2.5*fNumber) ; 65 newton0 += (15.0 + 6.25 * alpha) / (1.0 << 47 } 66 } << 48 else 67 else << 49 { 68 { << 50 cofi = i - 2 ; 69 cofi = i - 2; << 51 newton += ((1.0+2.55*cofi)/(1.9*cofi) + 1.26*cofi*alpha/(1.0+3.5*cofi))* 70 newton0 += ((1.0 + 2.55 * cofi) / (1.9 * << 52 (newton - fAbscissa[i-3])/(1.0 + 0.3*alpha) ; 71 1.26 * cofi * alpha / (1.0 + << 53 } 72 (newton0 - fAbscissa[i - 3]) << 54 for(k=1;k<=maxNumber;k++) 73 } << 74 for(k = 1; k <= maxNumber; ++k) << 75 { << 76 temp1 = 1.0; << 77 temp2 = 0.0; << 78 for(G4int j = 1; j <= fNumber; ++j) << 79 { 55 { 80 temp3 = temp2; << 56 temp1 = 1.0 ; 81 temp2 = temp1; << 57 temp2 = 0.0 ; 82 temp1 = << 58 for(j=1;j<=fNumber;j++) 83 ((2 * j - 1 + alpha - newton0) * tem << 59 { >> 60 temp3 = temp2 ; >> 61 temp2 = temp1 ; >> 62 temp1 = ((2*j - 1 + alpha - newton)*temp2 - (j - 1 + alpha)*temp3)/j ; >> 63 } >> 64 temp = (fNumber*temp1 - (fNumber +alpha)*temp2)/newton ; >> 65 newton1 = newton ; >> 66 newton = newton1 - temp1/temp ; >> 67 if(fabs(newton - newton1) <= tolerance) >> 68 { >> 69 break ; >> 70 } 84 } 71 } 85 temp = (fNumber * temp1 - (fNumber + << 72 if(k > maxNumber) 86 newton1 = newton0; << 87 newton0 = newton1 - temp1 / temp; << 88 if(std::fabs(newton0 - newton1) <= toler << 89 { 73 { 90 break; << 74 G4Exception("Too many iterations in Gauss-Laguerre constructor") ; 91 } 75 } 92 } << 76 93 if(k > maxNumber) << 77 fAbscissa[i-1] = newton ; 94 { << 78 fWeight[i-1] = -exp(GammaLogarithm(alpha + fNumber) - 95 G4Exception("G4GaussLaguerreQ::G4GaussLa << 79 GammaLogarithm((G4double)fNumber))/(temp*fNumber*temp2) ; 96 FatalException, << 80 } 97 "Too many iterations in Gaus << 98 } << 99 << 100 fAbscissa[i - 1] = newton0; << 101 fWeight[i - 1] = -std::exp(GammaLogarith << 102 GammaLogarithm( << 103 (temp * fNumber * temp2); << 104 } << 105 } 81 } 106 82 107 // ------------------------------------------- 83 // ----------------------------------------------------------------- 108 // 84 // 109 // Gauss-Laguerre method for integration of << 85 // Gauss-Laguerre method for integration of pow(x,alpha)*exp(-x)*pFunction(x) 110 // std::pow(x,alpha)*std::exp(-x)*pFunction(x) << 86 // from zero up to infinity. pFunction is evaluated in fNumber points for which 111 // from zero up to infinity. pFunction is eval << 87 // fAbscissa[i] and fWeight[i] arrays were created in 112 // for which fAbscissa[i] and fWeight[i] array << 113 // G4VGaussianQuadrature(double,int) construct 88 // G4VGaussianQuadrature(double,int) constructor 114 89 115 G4double G4GaussLaguerreQ::Integral() const << 90 G4double >> 91 G4GaussLaguerreQ::Integral() const 116 { 92 { 117 G4double integral = 0.0; << 93 G4int i ; 118 for(G4int i = 0; i < fNumber; ++i) << 94 G4double integral = 0.0 ; 119 { << 95 for(i=0;i<fNumber;i++) 120 integral += fWeight[i] * fFunction(fAbscis << 96 { 121 } << 97 integral += fWeight[i]*fFunction(fAbscissa[i]) ; 122 return integral; << 98 } >> 99 return integral ; 123 } 100 } 124 101