{

  TH1F num("num","",10,0,10); 
  TH1F den("den","",10,0,10); 
  TH1F eff("eff","",10,0,10); 
  TH1F eff2("eff2","",10,0,10); 
  
  num.Sumw2();
  den.Sumw2();
  eff.Sumw2();
  eff2.Sumw2();

  TRandom r;
  for(int i=0;i<1000;i++)
    num.Fill(r.Rndm()*10);
  for(int i=0;i<1500;i++)
    den.Fill(r.Rndm()*10);

  cout << "***** Un-scaled case" << endl;

  eff.Divide(&num,&den,1,1,"B");
  for(int i=1;i<=10;i++) {
    double e = num.GetBinContent(i)/den.GetBinContent(i);
    double N = den.GetBinContent(i);
    cout << "error bin  " << i << " = " << eff.GetBinError(i) << endl;
    cout << "error calc " << i << " = " << sqrt(e*(1-e)/N) << endl;
  }
  
  num.Scale(100);
  den.Scale(100);

  cout << "***** Scaled case" << endl;
 
  eff2.Divide(&num,&den,1,1,"B");
  for(int i=1;i<=10;i++) {
    double e = num.GetBinContent(i)/den.GetBinContent(i);
    double N = den.GetBinContent(i);
    cout << "scaled error bin  " << i << " = " << eff2.GetBinError(i) << endl;
    cout << "scaled error calc " << i << " = " << sqrt(e*(1-e)/N) << endl;
  }
  
}