#include "TFile.h"
#include "TGraphErrors.h"
#include "TF1.h"
#include "TMath.h"

Double_t Fit1(Double_t *x, Double_t *par)
{
        Double_t arg1     = TMath::Log(0.01*x[0]);          // in keV
        Double_t arg2     = TMath::Log(0.001*x[0]);          // in keV

            Double_t fit_val = TMath::Exp(TMath::Power((TMath::Power((par[0]+par[1]*arg1+par[2]*arg1*arg1),(-1.0*par[3]))+TMath::Power((par[4]+par[5]*arg2+par[6]*arg2*arg2),(-1.0*par[3]))),(-1.0*1/par[3])))/1000.;
        return fit_val;
}

void efficiency_R() {
   TGraphErrors *g = new TGraphErrors("candle_32degree.txt", "%lg %lg %lg");
   ROOT::Math::MinimizerOptions::SetDefaultMaxFunctionCalls(1000000);
   TF1 *RT = new TF1("RT",Fit1,100.,1500.,7.);

   
   /*RT->SetParameter(0,16.);
   RT->SetParameter(1,7.5);
   RT->FixParameter(2,0.);
   RT->FixParameter(3,15.);
   RT->SetParameter(4,15.);
   RT->SetParameter(5,-0.78);
   RT->SetParameter(6,.015);*/

   RT->SetParameter(0,7.);
   RT->SetParameter(1,2.5);
   RT->SetParameter(2,-1.0);
   RT->FixParameter(3,0.8);
   RT->SetParameter(4,40.);
   RT->SetParameter(5,8.0);
   RT->SetParameter(6,15);


   RT->Draw("L");
   //g->SetMaximum(15000.);//along Y
   g->SetMaximum(1.5);//along Y	
   g->Fit("RT","IER");
   g->SetMarkerStyle(4);
   g->Draw("AP");
   g->SetTitle("Efficiency Vs Energy(keV);Energy;Efficiency");
   gStyle->SetOptFit(1111);  //showing the parameters on graph
   
   TPaveText *pt = new TPaveText(77.6016,12857.83,971.9464,14578.31);
   pt->SetBorderSize(0);
   pt->SetFillColor(0);
   pt->SetFillStyle(0);
   pt->AddText("Exp{[(P0+P1*X+P2*X*X)**(-P3)+(P4+P5*Y+P6*Y*Y)**(-P3)]**(-1/P3)}");
   pt->AddText("WITH     X = LOG (X/100)     &     Y = LOG (X/1000)");
   pt->Draw();

   /*double par[7];
   RT->GetChisquare();
   RT->GetParameters(par);
  // double a = 700.0, y;
  // y = RT->Eval(a);
  // cout << "y = "<<y<<endl;*/
}