TDFun_o.h

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#ifndef RAD_TDFun_o
#define RAD_TDFun_o
 
#include "TConstant.h"
#include <cmath>
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;
    }
  };
} // namespace rb
 
#endif // #ifndef RAD_TDFun