void fitproblem()
{

  /* Reset Root environment */
  gROOT->Reset();
  
  // TGraphErrors.
  TGraphErrors * gr1 = new TGraphErrors("Run00088842_5st_lateral55.txt","%lg %lg %lg ");
      
  /* Make Canvas */
  TCanvas *c1 = new TCanvas("c1","Study of Lateral distribution",200,10,700,900);
  c1->SetFillColor(10);
  c1->SetFillStyle(1001);
  
  // Fit   
  //TF1 *fit = new TF1("fit","-[0]*(x-2)^2-[1]*(x-2)+[2]",-2,2.8);            // this is a fit on the log-log scale
  TF1 *fit = new TF1("fit","pol2",-2,2.8);           
 

  gr1->Fit("fit","R"); 
  gr1->SetLineColor(kRed);
  
  // Plot graph on canvas;
  gStyle->SetOptFit(1111);
  gr1->Draw("A*");
  
}