G4GaussLaguerreQ Class Reference

#include <G4GaussLaguerreQ.hh>

Inheritance diagram for G4GaussLaguerreQ:

Collaboration diagram for G4GaussLaguerreQ:

Public Member Functions
	G4GaussLaguerreQ (function pFunction, G4double alpha, G4int nLaguerre)
G4double	Integral () const
Public Member Functions inherited from G4VGaussianQuadrature
	G4VGaussianQuadrature (function pFunction)
virtual	~G4VGaussianQuadrature ()
G4double	GetAbscissa (G4int index) const
G4double	GetWeight (G4int index) const
G4int	GetNumber () const

Additional Inherited Members
Protected Member Functions inherited from G4VGaussianQuadrature
G4double	GammaLogarithm (G4double xx)
Protected Attributes inherited from G4VGaussianQuadrature
function	fFunction
G4double *	fAbscissa
G4double *	fWeight
G4int	fNumber

Detailed Description

Definition at line 68 of file G4GaussLaguerreQ.hh.

Constructor & Destructor Documentation

G4GaussLaguerreQ::G4GaussLaguerreQ	(	function	pFunction,
		G4double	alpha,
		G4int	nLaguerre
	)

Definition at line 42 of file G4GaussLaguerreQ.cc.

   : G4VGaussianQuadrature(pFunction)
{
   const G4double tolerance = 1.0e-10 ;
   const G4int maxNumber = 12 ;
   G4int i=1, k=1 ;
   G4double newton0=0.0, newton1=0.0,
            temp1=0.0, temp2=0.0, temp3=0.0, temp=0.0, cofi=0.0 ;

   fNumber = nLaguerre ;
   fAbscissa = new G4double[fNumber] ;
   fWeight   = new G4double[fNumber] ;
      
   for(i=1;i<=fNumber;i++)      // Loop over the desired roots
   {
      if(i == 1)
      {
         newton0 = (1.0 + alpha)*(3.0 + 0.92*alpha)
                 / (1.0 + 2.4*fNumber + 1.8*alpha) ;
      }
      else if(i == 2)
      {
         newton0 += (15.0 + 6.25*alpha)/(1.0 + 0.9*alpha + 2.5*fNumber) ;
      }
      else
      {
         cofi = i - 2 ;
         newton0 += ((1.0+2.55*cofi)/(1.9*cofi)
                    + 1.26*cofi*alpha/(1.0+3.5*cofi))
                    * (newton0 - fAbscissa[i-3])/(1.0 + 0.3*alpha) ;
      }
      for(k=1;k<=maxNumber;k++)
      {
         temp1 = 1.0 ;
         temp2 = 0.0 ;
         for(G4int j=1;j<=fNumber;j++)
         {
            temp3 = temp2 ;
            temp2 = temp1 ;
            temp1 = ((2*j - 1 + alpha - newton0)*temp2
                     - (j - 1 + alpha)*temp3)/j ;
         }
         temp = (fNumber*temp1 - (fNumber +alpha)*temp2)/newton0 ;
         newton1 = newton0 ;
         newton0 = newton1 - temp1/temp ;
         if(std::fabs(newton0 - newton1) <= tolerance) 
         {
            break ;
         }
      }
      if(k > maxNumber)
      {
         G4Exception("G4GaussLaguerreQ::G4GaussLaguerreQ()",
                     "OutOfRange", FatalException,
                     "Too many iterations in Gauss-Laguerre constructor") ;
      }
         
      fAbscissa[i-1] = newton0 ;
      fWeight[i-1] = -std::exp(GammaLogarithm(alpha + fNumber)
                   - GammaLogarithm((G4double)fNumber))/(temp*fNumber*temp2) ;
   }
}

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Member Function Documentation

G4double G4GaussLaguerreQ::Integral

(

)

const

Definition at line 116 of file G4GaussLaguerreQ.cc.

{
   G4double integral = 0.0 ;
   for(G4int i=0;i<fNumber;i++)
   {
      integral += fWeight[i]*fFunction(fAbscissa[i]) ;
   }
   return integral ;
}

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The documentation for this class was generated from the following files:

• geant4.10.03.p01/source/global/HEPNumerics/include/G4GaussLaguerreQ.hh
• geant4.10.03.p01/source/global/HEPNumerics/src/G4GaussLaguerreQ.cc