EvtBtoXsgammaFermiUtil.hh

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 2001      Brunel University
//
// Module: EvtGen/EvtBtoXsgammaFermiUtil.hh
//
// Description:
//       Class to hold various fermi functions and their helper functions. The
//       fermi functions are used in EvtBtoXsgammaKagan.
//
// Modification history:
//
//       Jane Tinslay     March 21, 2001         Module created
//
//------------------------------------------------------------------------
 
#ifndef EVTBTOXSGAMMAFERMIUTIL_HH
#define EVTBTOXSGAMMAFERMIUTIL_HH
 
#include <vector>
 
class EvtBtoXsgammaFermiUtil {
 
  //--------------------
  // Instance Members --
  //--------------------
 
public:
  // Constructors
  EvtBtoXsgammaFermiUtil(){};
  virtual ~EvtBtoXsgammaFermiUtil(){};
 
  // Exponential function
  static double FermiExpFunc( double var, const std::vector<double>& coeffs );
 
  // Gaussian function and its helper functions
  static double FermiGaussFunc( double, std::vector<double> const& coeffs );
  static double FermiGaussFuncRoot( double, double, double, std::vector<double>& coeffs );
  static double FermiGaussRootFcnA( double, const std::vector<double>& coeffs1,
                                    const std::vector<double>& coeffs2 );
  static double FermiGaussRootFcnB( double, const std::vector<double>& coeffs1,
                                    const std::vector<double>& coeffs2 );
  static double Gamma( double, const std::vector<double>& coeffs );
 
  // Roman function and its helper functions
  static double BesselI1( double );
  static double BesselK1( double );
  static double FermiRomanFuncRoot( double, double );
  static double FermiRomanRootFcnA( double );
  static double FermiRomanFunc( double, std::vector<double> const& coeffs );
};
 
#endif