G4SimpleIntegration.hh

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//
//
// Class description:
//
// Class for realisation of simple numerical methodes for integration of
// functions with signature: double f(double). The methods based mainly on
// algorithms given in the book :
//   An introduction to NUMERICAL METHODS IN C++,
//   B.H. Flowers, Claredon Press, Oxford, 1995.
//
// --------------------------- Member data ----------------------------
//
//   fFunction       - pointer to the function to be integrated
//   fTolerance      - accuracy of integration in Adaptive Gauss method
//   fMaxDepth = 100 - constant maximum iteration depth for
//                     Adaptive Gauss method
//
// --------------------------- Methods --------------------------------
//
//   Trapezoidal, MidPoint, Gauss and Simpson(double a,double b,int n)
//   - integrate function pointed by fFunction from a to b by n iterations,
//     i.e. with Step (b-a)/n according to the correspondent method.
//
//   AdaptGausIntegration(double a, double b)
//   - integrate function from a to be with accuracy <= fTolerance 

// ----------------------------- History ------------------------------ 
//
//  26.03.97   V.Grichine ( Vladimir.Grichine@cern.ch )

#ifndef G4SIMPLEINTEGRATION_HH
#define G4SIMPLEINTEGRATION_HH

#include "G4Types.hh"

typedef G4double (*function)(G4double) ;

class G4SimpleIntegration
{
  public:

       explicit G4SimpleIntegration( function pFunction ) ;
       
       G4SimpleIntegration( function pFunction,
                            G4double pTolerance ) ;
       
      ~G4SimpleIntegration() ;
       
       // Simple integration methods
       
       G4double Trapezoidal(G4double xInitial,
                            G4double xFinal,
                            G4int iterationNumber ) ;

       G4double    MidPoint(G4double xInitial,
                            G4double xFinal,
                            G4int iterationNumber ) ;

       G4double       Gauss(G4double xInitial,
                            G4double xFinal,
                            G4int iterationNumber ) ;

       G4double     Simpson(G4double xInitial,
                            G4double xFinal,
                            G4int iterationNumber ) ;

       // Adaptive Gauss integration with accuracy ~ fTolerance

       G4double       AdaptGaussIntegration( G4double xInitial,
                                             G4double xFinal   ) ;
       
  protected:

       G4double       Gauss( G4double xInitial,
                             G4double xFinal   ) ;

       void      AdaptGauss( G4double xInitial,
                             G4double xFinal,
                             G4double& sum,
                             G4int& depth      ) ;
  private:

       G4SimpleIntegration(const G4SimpleIntegration&);
       G4SimpleIntegration& operator=(const G4SimpleIntegration&);
         // Private copy constructor and assignment operator.

  private:

        function fFunction ;
        G4double fTolerance ;
        const G4int fMaxDepth ;
};

#endif