Gabriele Cosmo
61 lines
1.6 KiB
C++
61 lines
1.6 KiB
C++
// This code implementation is the intellectual property of
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// the GEANT4 collaboration.
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//
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// By copying, distributing or modifying the Program (or any work
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// based on the Program) you indicate your acceptance of this statement,
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// and all its terms.
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//
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// $Id: G4GaussChebyshevQ.cc,v 1.2 1999/11/16 17:31:09 gcosmo Exp $
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// GEANT4 tag $Name: geant4-01-00 $
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//
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#include "G4GaussChebyshevQ.hh"
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// -----------------------------------------------------
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//
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// Constructor for Gauss-Chebyshev quadrature method
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G4GaussChebyshevQ::G4GaussChebyshevQ( function pFunction ,
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G4int nChebyshev )
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: G4VGaussianQuadrature(pFunction)
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{
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G4int i ;
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fNumber = nChebyshev ; // Try to reduce fNumber twice ??
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G4double cof = pi/fNumber ;
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fAbscissa = new G4double[fNumber] ;
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fWeight = new G4double[fNumber] ;
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for(i=0;i<fNumber;i++)
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{
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fAbscissa[i] = cos(cof*(i + 0.5)) ;
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fWeight[i] = cof*sqrt(1 - fAbscissa[i]*fAbscissa[i]) ;
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}
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}
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// ----------------------------------------------------------------------
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//
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G4GaussChebyshevQ::~G4GaussChebyshevQ()
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{
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;
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}
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// -------------------------------------------------------------------------------
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//
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// Integrates function pointed by fFunction from a to b by Gauss-Chebyshev
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// quadrature method
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G4double
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G4GaussChebyshevQ::Integral(G4double a, G4double b) const
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{
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G4int i ;
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G4double xDiff, xMean, dx, integral = 0.0 ;
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xMean = 0.5*(a + b) ;
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xDiff = 0.5*(b - a) ;
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for(i=0;i<fNumber;i++)
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{
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dx = xDiff*fAbscissa[i] ;
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integral += fWeight[i]*fFunction(xMean + dx) ;
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}
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return integral *= xDiff ;
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}
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