include/Geant4/G4GaussLaguerreQ.hh

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0025 //
0026 //
0027 //
0028 // Class description:
0029 //
0030 // Class for realization of Gauss-Laguerre quadrature method
0031 // Roots of ortogonal polynoms and corresponding weights are calculated based on
0032 // iteration method (by bisection Newton algorithm). Constant values for initial
0033 // approximations were derived from the book:
0034 //   M. Abramowitz, I. Stegun, Handbook of mathematical functions,
0035 //   DOVER Publications INC, New York 1965 ; chapters 9, 10, and 22.
0036
0037 // Author: V.Grichine, 13.05.1997
0038 // --------------------------------------------------------------------
0039 #ifndef G4GAUSSLAGUERREQ_HH
0040 #define G4GAUSSLAGUERREQ_HH 1
0041
0042 #include "G4VGaussianQuadrature.hh"
0043
0044 class G4GaussLaguerreQ : public G4VGaussianQuadrature
0045 {
0046  public:
0047   G4GaussLaguerreQ(function pFunction, G4double alpha, G4int nLaguerre);
0048   // Constructor for Gauss-Laguerre quadrature method: integral from zero to
0049   // infinity of std::pow(x,alpha)*std::exp(-x)*f(x). The value of nLaguerre
0050   // sets the accuracy.
0051   // The constructor creates arrays fAbscissa[0,..,nLaguerre-1] and
0052   // fWeight[0,..,nLaguerre-1] . The function GaussLaguerre(f) should be
0053   // called then with any f.
0054
0055   G4GaussLaguerreQ(const G4GaussLaguerreQ&) = delete;
0056   G4GaussLaguerreQ& operator=(const G4GaussLaguerreQ&) = delete;
0057
0058   G4double Integral() const;
0059   // Gauss-Laguerre method for integration of
0060   // std::pow(x,alpha)*std::exp(-x)*pFunction(x) from zero up to infinity.
0061   // pFunction is evaluated in fNumber points for which fAbscissa[i] and
0062   // fWeight[i] arrays were created in constructor.
0063 };
0064
0065 #endif