G4VGaussianQuadrature.hh

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// $Id$
//
// Class description:
//
// Base Class for realisation of numerical methodes for integration of functions
// with signature double f(double) by Gaussian quadrature methods
// Roots of ortogonal polynoms and corresponding weights are calculated based on
// iteration method (by bisection Newton algorithm). Constant values for initial
// approximations were derived from the book: M. Abramowitz, I. Stegun, Handbook
// of mathematical functions, DOVER Publications INC, New York 1965 ; chapters 9,
// 10, and 22 .
//
// ---------------------------- Member data: ----------------------------------
//
//  fFunction  - pointer to the function to be integrated
//  fNumber    - the number of points in fAbscissa and fWeight arrays
//  fAbscissa  - array of abscissas, where function will be evaluated
//  fWeight    - array of corresponding weights
//
//
// ----------------------------------------------------------------------
//
// Auxiliary function which returns the value of std::log(gamma-function(x))
//
// G4double 
// GammaLogarithm(G4double xx)
 
// ------------------------------------------------------------------------------
//
// History:
//             18.04.97   V.Grichine ( Vladimir.Grichine@cern.ch )
 
#ifndef G4VGAUSSIANQUADRATURE_HH
#define G4VGAUSSIANQUADRATURE_HH
 
#include "globals.hh"
 
typedef G4double (*function)(G4double) ;
 
class G4VGaussianQuadrature
{
  public:
 
    explicit G4VGaussianQuadrature( function pFunction ) ;
      // Base constructor
 
    virtual ~G4VGaussianQuadrature() ;
      // Virtual destructor     
 
    G4double GetAbscissa(G4int index) const ;
    G4double GetWeight(G4int index) const ;
    G4int    GetNumber() const;
      // Access functions
 
  protected:
 
    G4double GammaLogarithm(G4double xx) ;
 
    //  Data members common for GaussianQuadrature family
    //
    function  fFunction ;
    G4double* fAbscissa ;
    G4double* fWeight ;
    G4int     fNumber ;
 
  private:
 
    G4VGaussianQuadrature(const G4VGaussianQuadrature&);
    G4VGaussianQuadrature& operator=(const G4VGaussianQuadrature&);
};
 
#endif