TDFun_o.h

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#ifndef RAD_TDFun_o
#define RAD_TDFun_o
 
#include <cmath>
#include "TConstant.h"
namespace rb{
class TDFun{
protected:
  double fD0;
  double fiD0;
  double fb2;
  double fib2;
public:
  TDFun();
 
  TDFun(const double& E){
    double L    = 2.*log(2.*E/me);
    double fBeta = 2.*alpha/M_PI*(L-1.);
    fb2  = fBeta/2;
    fib2 = 1/fb2;
    //  fD0   = 1.+3./8.*fBeta-fBeta*fBeta/48.*(gConst->Pi2() + fL/3. - 47./8.);
    fD0  = 1.+3./8.*fBeta+fBeta*fBeta/16.*(9./8. - M_PI*M_PI/3);
    fiD0 = 1/fD0;
  }
 
  ~TDFun(){};
 
  inline double GetD0() const { return fD0;};
  inline double GetiD0() const { return fiD0;};
  inline double GetBeta2() const { return fb2;};
  inline double GetiBeta2() const { return fib2;};
 
  inline double Eval(const double &z){  
    double x = 1 - z;
    //    double D = fb2*pow(x,fb2-1)*fD0 - 0.5*fb2*(1+z) - 
    //      fb2*fb2/8*(4*(1+z)*log(x)+(1+3*z*z)/x*log(z)+5+z);
    double D = fb2*pow(x,fb2-1)*fD0 - 0.5*fb2*(1+z) - 
      fb2*fb2/8*(4*(1+z)*log(x)+(1+3*z*z)/x*log1p(-x)+5+z);
    return D;
  }
 
  inline double Eval(const double &z, const double &b2, const double &D0){
    double x = 1 - z;
    //    double D = b2*pow(x,b2-1)*D0 - 0.5*b2*(1+z) - 
    //      b2*b2/8*(4*(1+z)*log(x)+(1+3*z*z)/x*log(z)+5+z);
    double D = b2*pow(x,b2-1)*D0 - 0.5*b2*(1+z) - 
      b2*b2/8*(4*(1+z)*log(x)+(1+3*z*z)/x*log1p(-x)+5+z);
    return D;
  }
 
  inline double EvalSoft(const double &x){
    double z  = 1 - x;
    double lx = log(x);
    double t1 = exp(-fb2*lx);
    double t2 = t1*x;
    //    double D  = fD0 - t2*(0.5*(1+z) + fb2/8*( 4*(1+z)*lx + 4 + (1+z))) - 
    //      fb2/8*t1*(1+3*z*z)*log(z);
    double D  = fD0 - t2*(0.5*(1+z) + fb2/8*( 4*(1+z)*lx + 4 + (1+z))) - 
      fb2/8*t1*(1+3*z*z)*log1p(-x);
    return D;
  }
 
  inline double EvalSoft(const double &x, const double &b2, const double &D0){
    double z  = 1 - x;
    double lx = log(x);
    double t1 = exp(-b2*lx);
    double t2 = t1*x;
    //    double D  = D0 - t2*(0.5*(1+z) + b2/8*( 4*(1+z)*lx + 4 + (1+z))) - 
    //      b2/8*t1*(1+3*z*z)*log(z);
    double D  = D0 - t2*(0.5*(1+z) + b2/8*( 4*(1+z)*lx + 4 + (1+z))) - 
      b2/8*t1*(1+3*z*z)*log1p(-x);
    return D;
  }
 
};
}
 
#endif //#ifndef RAD_TDFun