00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // $Id$ 00028 // 00029 #include "G4GaussChebyshevQ.hh" 00030 #include "G4PhysicalConstants.hh" 00031 00032 // ----------------------------------------------------- 00033 // 00034 // Constructor for Gauss-Chebyshev quadrature method 00035 00036 G4GaussChebyshevQ::G4GaussChebyshevQ( function pFunction , 00037 G4int nChebyshev ) 00038 : G4VGaussianQuadrature(pFunction) 00039 { 00040 fNumber = nChebyshev ; // Try to reduce fNumber twice ?? 00041 G4double cof = pi/fNumber ; 00042 fAbscissa = new G4double[fNumber] ; 00043 fWeight = new G4double[fNumber] ; 00044 for(G4int i=0;i<fNumber;i++) 00045 { 00046 fAbscissa[i] = std::cos(cof*(i + 0.5)) ; 00047 fWeight[i] = cof*std::sqrt(1 - fAbscissa[i]*fAbscissa[i]) ; 00048 } 00049 } 00050 00051 // ---------------------------------------------------------------------- 00052 // 00053 00054 G4GaussChebyshevQ::~G4GaussChebyshevQ() 00055 { 00056 } 00057 00058 // ------------------------------------------------------------------------------- 00059 // 00060 // Integrates function pointed by fFunction from a to b by Gauss-Chebyshev 00061 // quadrature method 00062 00063 G4double 00064 G4GaussChebyshevQ::Integral(G4double a, G4double b) const 00065 { 00066 G4double xDiff=0.5*(b - a), 00067 xMean=0.5*(a + b), 00068 dx=0.0, integral=0.0 ; 00069 00070 for(G4int i=0;i<fNumber;i++) 00071 { 00072 dx = xDiff*fAbscissa[i] ; 00073 integral += fWeight[i]*fFunction(xMean + dx) ; 00074 } 00075 return integral *= xDiff ; 00076 }