#include "TFile.h"
#include "TGraphErrors.h"
#include "TF1.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("rad_9.txt", "%lg %lg %lg");
   TF1 *RT = new TF1("RT",Fit1,100.,1500.,7.);
   /*RT->SetParameter(0,13.);
   RT->SetParameter(1,-0.3);
   RT->SetParameter(2,0.);
   RT->SetParameter(3,15.);
   RT->SetParameter(4,5.);
   RT->SetParameter(5,5.);
   RT->SetParameter(6,10.);*/

   //rad 6,7
   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);
 
   //rough	
   /*RT->SetParameter(0,1.);
   RT->SetParameter(1,1.);
   RT->SetParameter(2,1.);
   RT->SetParameter(3,1.);
   RT->SetParameter(4,1.);
   RT->SetParameter(5,1.);
   RT->SetParameter(6,1.);*/

   RT->Draw("L");
   g->SetMaximum(15000.);//along Y
   g->Fit("RT","IER");
   g->SetMarkerStyle(3);
   g->Draw("AP");
   g->SetTitle("Efficiency Vs Energy(keV);Energy;Efficiency");
   gStyle->SetOptFit(0111);  //showing the parameters on graph
   TPaveText *pt = new TPaveText();
   pt->AddText("Exp{[(P0+P1*X+P2*X*X)**(-P3)+(P4+P5*Y+P6*Y*Y)**(-P3)]**(-1/P3)}");
   pt->Draw();
   TPaveText *pt1 = new TPaveText();
   pt1->AddText("WITH     X = LOG (X/100)     &     Y = LOG (X/1000)");//next line
   pt1->Draw();
   double par[7];
   RT->GetChisquare();
   RT->GetParameters(par);
   double a = 700.0, y;   
   y = RT->Eval(a);   
   cout << "y = "<<y<<endl;   
}