Gabriele Cosmo
90 lines
2.6 KiB
C++
90 lines
2.6 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: G4VGaussianQuadrature.hh,v 1.2 1999/11/16 17:30:59 gcosmo Exp $
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// GEANT4 tag $Name: geant4-01-00 $
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//
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// Class description:
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//
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// Base Class for realisation of numerical methodes for integration of functions
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// with signature double f(double) by Gaussian quadrature methods
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// Roots of ortogonal polynoms and corresponding weights are calculated based on
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// iteration method (by bisection Newton algorithm). Constant values for initial
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// approximations were derived from the book: M. Abramowitz, I. Stegun, Handbook
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// of mathematical functions, DOVER Publications INC, New York 1965 ; chapters 9,
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// 10, and 22 .
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//
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// ---------------------------- Member data: ----------------------------------
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//
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// fFunction - pointer to the function to be integrated
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// fNumber - the number of points in fAbscissa and fWeight arrays
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// fAbscissa - array of abscissas, where function will be evaluated
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// fWeight - array of corresponding weights
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//
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//
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// ----------------------------------------------------------------------
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//
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// Auxiliary function which returns the value of log(gamma-function(x))
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//
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// G4double
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// GammaLogarithm(G4double xx)
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// ------------------------------------------------------------------------------
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//
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// History:
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// 18.04.97 V.Grichine ( Vladimir.Grichine@cern.ch )
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#ifndef G4VGAUSSIANQUADRATURE_HH
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#define G4VGAUSSIANQUADRATURE_HH
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#include "globals.hh"
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typedef G4double (*function)(G4double) ;
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class G4VGaussianQuadrature
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{
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public:
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// Base constructor
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G4VGaussianQuadrature( function pFunction ) ;
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// Virtual destructor
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virtual ~G4VGaussianQuadrature() ;
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// Access functions:
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G4double GetAbscissa(G4int index) const ;
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G4double GetWeight(G4int index) const ;
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G4int GetNumber() const { return fNumber ; }
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// Methods:
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// virtual G4double DefiniteIntegral( G4double a,
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// G4double b ) const = 0 ;
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// virtual G4double Integral() const = 0 ;
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protected:
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G4double GammaLogarithm(G4double xx) ;
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// Data members common for GaussianQuadrature family
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function fFunction ;
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G4double* fAbscissa ;
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G4double* fWeight ;
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G4int fNumber ;
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private:
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} ;
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#endif
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