| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These *
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| 9 | // * include a list of copyright holders. *
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| 10 | // * *
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| 11 | // * Neither the authors of this software system, nor their employing *
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| 12 | // * institutes,nor the agencies providing financial support for this *
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| 13 | // * work make any representation or warranty, express or implied, *
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| 14 | // * regarding this software system or assume any liability for its *
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| 15 | // * use. Please see the license in the file LICENSE and URL above *
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| 16 | // * for the full disclaimer and the limitation of liability. *
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| 17 | // * *
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| 18 | // * This code implementation is the result of the scientific and *
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| 19 | // * technical work of the GEANT4 collaboration. *
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| 20 | // * By using, copying, modifying or distributing the software (or *
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| 21 | // * any work based on the software) you agree to acknowledge its *
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| 22 | // * use in resulting scientific publications, and indicate your *
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| 23 | // * acceptance of all terms of the Geant4 Software license. *
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| 24 | // ********************************************************************
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| 25 | //
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| 26 | //
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| 27 | // $Id: G4GaussChebyshevQ.cc,v 1.6 2006/06/29 19:00:07 gunter Exp $
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| 28 | // GEANT4 tag $Name: geant4-09-02-ref-02 $
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| 29 | //
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| 30 | #include "G4GaussChebyshevQ.hh"
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| 31 |
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| 32 | // -----------------------------------------------------
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| 33 | //
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| 34 | // Constructor for Gauss-Chebyshev quadrature method
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| 35 |
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| 36 | G4GaussChebyshevQ::G4GaussChebyshevQ( function pFunction ,
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| 37 | G4int nChebyshev )
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| 38 | : G4VGaussianQuadrature(pFunction)
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| 39 | {
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| 40 | fNumber = nChebyshev ; // Try to reduce fNumber twice ??
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| 41 | G4double cof = pi/fNumber ;
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| 42 | fAbscissa = new G4double[fNumber] ;
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| 43 | fWeight = new G4double[fNumber] ;
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| 44 | for(G4int i=0;i<fNumber;i++)
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| 45 | {
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| 46 | fAbscissa[i] = std::cos(cof*(i + 0.5)) ;
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| 47 | fWeight[i] = cof*std::sqrt(1 - fAbscissa[i]*fAbscissa[i]) ;
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| 48 | }
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| 49 | }
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| 50 |
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| 51 | // ----------------------------------------------------------------------
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| 52 | //
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| 53 |
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| 54 | G4GaussChebyshevQ::~G4GaussChebyshevQ()
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| 55 | {
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| 56 | }
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| 57 |
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| 58 | // -------------------------------------------------------------------------------
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| 59 | //
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| 60 | // Integrates function pointed by fFunction from a to b by Gauss-Chebyshev
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| 61 | // quadrature method
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| 62 |
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| 63 | G4double
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| 64 | G4GaussChebyshevQ::Integral(G4double a, G4double b) const
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| 65 | {
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| 66 | G4double xDiff=0.5*(b - a),
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| 67 | xMean=0.5*(a + b),
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| 68 | dx=0.0, integral=0.0 ;
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| 69 |
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| 70 | for(G4int i=0;i<fNumber;i++)
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| 71 | {
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| 72 | dx = xDiff*fAbscissa[i] ;
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| 73 | integral += fWeight[i]*fFunction(xMean + dx) ;
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| 74 | }
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| 75 | return integral *= xDiff ;
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| 76 | }
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