Double_t CalculateNLL(Double_t *par)
{
  Double_t fval = 0.0;
  Int_t nx = hist->GetNbinsX();
  Int_t ny = hist->GetNbinsY();

  for(Int_t ix = 1; ix <= nx; ix++)
  {
    for(Int_t iy = 1; iy <= ny; iy++)
    {
      Int_t MC_N = hist->GetBinContent(ix, iy);
      Double_t x_f_2 = 0.04*ix - 0.02;
      Double_t costheta_2 = 0.04*iy -1.02;
      Double_t pdf = (1.5*B_f*M_PI*beta_val*alpha*alpha*Function_Theta(x_f_2, costheta_2, par))/s;

      //Lum : 1e9 pb  , cross section : pb-1
      Double_t mu = pdf*0.04*0.04*1e9*3.87e8;

      Double_t Li = pow(mu,MC_N)*exp(-mu);


      if (mu > 0) {
              fval += mu - MC_N * log(mu);
               fval += logFactorial(MC_N);

      }
    }
  }
  return fval;

}


void FCN_NLL(Int_t &npar, Double_t *gin,
             Double_t &fval, Double_t *par, Int_t iflag)
{

  fval = CalculateNLL(par);
}



void Fit_chis_WithoutScan_Delta_AY_Reco()

{

  PrepareHistogram();

  TMinuit *mMinuit = new TMinuit(3);
  mMinuit->SetFCN(FCN_NLL);

  Double_t arglist[10];
  Int_t ierflg = 0;

  arglist[0] = 2;
  mMinuit->mnexcm("SET PRI", arglist, 1, ierflg);
  arglist[0] = 0.5;
  mMinuit->mnexcm("SET ERR", arglist, 1, ierflg);

  Double_t step  = 0.0001;
  mMinuit->mnparm(0, "deltaAy", 0.001, step, 0.0, 0.0, ierflg);
  mMinuit->mnparm(1, "deltaAz", 0.001, step, 0.0, 0.0, ierflg);
  mMinuit->mnparm(2, "deltaBz", 0.001, step, 0.0, 0.0, ierflg);

  
  arglist[0] = 50000;
  arglist[1] = 1e-5;
  mMinuit->mnexcm("MIGRAD", arglist, 2, ierflg);
  mMinuit->mnexcm("HESSE", 0, 0, ierflg);

  
}