algebraic_fitting_function.cpp

#include "algebraic_fitting_function.h"
 
templateClassImp(KVImpactParameters::algebraic_fitting_function)
 
namespace KVImpactParameters {
 
 
 
   algebraic_fitting_function::algebraic_fitting_function(const algebraic_fitting_function& other)
      : params(other.params)
   {
   }
 
 
 
 
   algebraic_fitting_function::algebraic_fitting_function(double alph, double gam, double thet, double Xmi, double Xma)
   {
      double p[] = {thet, Xma, Xmi, alph, gam};
      fill_params_from_array(p);
   }
 
 
 
 
   double algebraic_fitting_function::k_cb(double cb) const
   {
      if (params.alpha.value <= 0) return 0;
      if (params.gamma.value <= 0) return 0;
      if (cb < 0 || cb > 1) return 0;
      double arg = 1. - TMath::Power(cb, params.alpha.value);
      if (arg < 0) return 0;
      return params.kmax.value * TMath::Power(arg, params.gamma.value) + params.k0.value;
   }
 
 
 
 
   void algebraic_fitting_function::fill_params_from_array(double* p)
   {
      params.theta.value = p[0];
      params.Xmax.value = p[1];
      params.k0.value = p[2] / p[0];
      params.kmax.value = params.Xmax.value / params.theta.value - params.k0.value;
      params.alpha.value = p[3];
      params.gamma.value = p[4];
   }
 
 
 
 
   void algebraic_fitting_function::fill_array_from_params(double* p) const
   {
      p[0] = params.theta.value;
      p[1] = params.Xmax.value;
      p[2] = params.theta.value * params.k0.value;
      p[3] = params.alpha.value;
      p[4] = params.gamma.value;
   }
 
 
 
 
   void algebraic_fitting_function::set_par_names(TF1& f) const
   {
      f.SetParNames("#theta", "X_{max}", "X_{min}", "#alpha", "#gamma");
   }
 
 
 
 
   void algebraic_fitting_function::set_initial_parameters(TH1* h, TF1& f)
   {
      f.SetParameter(0, params.theta.value = 0.5);
      f.SetParLimits(0, 0.1, 100.);
      double xmax = h->GetXaxis()->GetBinUpEdge(h->GetNbinsX());
      double xmin = xmax / 7.;
      f.SetParameter(1, params.Xmax.value = xmin * 2);
      f.SetParLimits(1, xmin, xmax);
      f.SetParameter(2, params.k0.value = 0);
      f.SetParLimits(2, 0, xmin);
      f.SetParameter(3, params.alpha.value = 1);
      f.SetParLimits(3, 0.1, 5);
      f.SetParameter(4, params.gamma.value = 1);
      f.SetParLimits(4, 0.1, 10);
   }
 
 
}