include/Geant4/G4VGaussianQuadrature.hh

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0025 //
0026 // G4VGaussianQuadrature
0027 //
0028 // Class description:
0029 //
0030 // Base Class for realisation of numerical methodes for integration of functions
0031 // with signature double f(double) by Gaussian quadrature methods
0032 // Roots of ortogonal polynoms and corresponding weights are calculated based on
0033 // iteration method (by bisection Newton algorithm). Constant values for initial
0034 // approximations were derived from the book:
0035 //   M. Abramowitz, I. Stegun, Handbook of mathematical functions,
0036 //   DOVER Publications INC, New York 1965 ; chapters 9, 10, and 22.
0037
0038 // Author: V.Grichine, 18.04.1997
0039 // --------------------------------------------------------------------
0040 #ifndef G4VGAUSSIANQUADRATURE_HH
0041 #define G4VGAUSSIANQUADRATURE_HH 1
0042
0043 #include "globals.hh"
0044
0045 using function = G4double (*)(G4double);
0046
0047 class G4VGaussianQuadrature
0048 {
0049  public:
0050   explicit G4VGaussianQuadrature(function pFunction);
0051   // Base constructor
0052
0053   virtual ~G4VGaussianQuadrature();
0054   // Virtual destructor
0055
0056   G4VGaussianQuadrature(const G4VGaussianQuadrature&) = delete;
0057   G4VGaussianQuadrature& operator=(const G4VGaussianQuadrature&) = delete;
0058
0059   G4double GetAbscissa(G4int index) const;
0060   G4double GetWeight(G4int index) const;
0061   G4int GetNumber() const;
0062   // Access functions
0063
0064  protected:
0065   G4double GammaLogarithm(G4double xx);
0066   // Auxiliary function which returns the value of std::log(gamma-function(x))
0067
0068   //  Data members common for GaussianQuadrature family
0069   //
0070   function fFunction;             // pointer to the function to be integrated
0071   G4double* fAbscissa = nullptr;  // array of abscissas
0072   G4double* fWeight   = nullptr;  // array of corresponding weights
0073   G4int fNumber = 0;  // the number of points in fAbscissa and fWeight arrays
0074 };
0075
0076 #endif