Bessel.hh

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// -*- C++ -*-
// $Id: Bessel.hh,v 1.2 2003/09/06 14:04:13 boudreau Exp $
//---------------------Bessel-------------------------------------------------//
//                                                                            //
// Class Bessel, providing Bessel Functions  The Namespace "FractionalORder"  //
// and "Integral order" are nested here, so that you fully specify the class  //
// like this:                                                                 //
//                                                                            //
//                 Genfun::FractionalOrder::Bessel                            //
//                                                                            //
//                              or                                            //
//                                                                            //
//                 Genfun::IntegralOrder::Bessel                              //
//                                                                            //
//                                                                            //
// Joe Boudreau, April 2001                                                   //
//                                                                            //
//--------------------------------------------------------------------------  //
#ifndef Bessel_h
#define Bessel_h 1
#include "CLHEP/GenericFunctions/AbsFunction.hh"
#include "CLHEP/GenericFunctions/Parameter.hh"
namespace Genfun {
 
namespace FractionalOrder { 
  /**
   * @author
   * @ingroup genfun
   */
  class Bessel : public AbsFunction  {
 
    FUNCTION_OBJECT_DEF(Bessel)
 
      public:
 
    // Enumerated type:
    enum Type {J, Y};
 
    // Constructor:  Use this one and you will get a Bessel function of
    // integer order
    Bessel (Type type);
 
    // Copy constructor
    Bessel(const Bessel &right);
  
    // Destructor
    virtual ~Bessel();
  
    // Retreive function value
    virtual double operator ()(double argument) const override;
    virtual double operator ()(const Argument & a) const override {return operator() (a[0]);}
  
    // Get the order of the Bessel Function.  Default value, 0.0.  If modified the
    // Bessel function 
    Parameter & order(); 
    const Parameter & order() const; 
 
  private:
 
    // It is illegal to assign an adjustable constant
    const Bessel & operator=(const Bessel &right);
 
    // The type and order of the Bessel function
    Type      _type;
    Parameter _order; // the fractional order:
  
  };
} // namespace FractionalOrder
 
namespace IntegralOrder { 
  /**
   * @author
   * @ingroup genfun
   */
  class Bessel : public AbsFunction  {
 
    FUNCTION_OBJECT_DEF(Bessel)
 
      public:
 
    // Enumerated type:
    enum Type {J, Y};
 
    // Constructor:  Use this one and you will get a Bessel function of
    // integer order
    Bessel (Type type, unsigned int order);
 
    // Copy constructor
    Bessel(const Bessel &right);
  
    // Destructor
    virtual ~Bessel();
  
    // Retreive function value
    virtual double operator ()(double argument) const override;
    virtual double operator ()(const Argument & a) const override {return operator() (a[0]);}
  
  private:
 
    // It is illegal to assign an adjustable constant
    const Bessel & operator=(const Bessel &right);
 
    // The type and order of the Bessel function
    Type                _type;
    unsigned  int       _order; 
 
    double              _bessel_IJ_taylor(double nu, 
                      double x,
                      int sign,
                      int kmax,
                      double threshhold) const;
  
  };
} // namespace IntegralOrder
 
} // namespace Genfun
 
 
#include "CLHEP/GenericFunctions/Bessel.icc"
#endif