void muidll1eff()
{
  gStyle->SetOptFit(11);
  gStyle->SetOptStat(0);

  double low = 0.8;
  double high = 1.0;
  double binwidth = 0.01;
  int nbins = (int) ((high - low)/binwidth + 0.5);

  nbins++; 
  double hlow = low - binwidth/2;
  double hhigh = high + binwidth/2;

  cout << " nbins " << nbins
       << " hlow " << hlow
       << " hhigh " << hhigh
       << endl;

  TH1F *h3 = new TH1F("h3","3 and 4, out of 5",nbins,hlow,hhigh);
  TH1F *h4 = new TH1F("h4","3 and 4, out of 5",nbins,hlow,hhigh);

  for (int i = 0; i<nbins; i++)
    {
      double eff = low + i*binwidth;

      double all = pow(eff,5);
      double rest4 = 5*pow(eff,4)*(1-eff); // 1 is missed, could be in any gap

      double rest3 = 9*pow(eff,3)*(1-eff)*(1-eff); // any 2 gaps missing; except 
      // that 0 and 1 can not be missing together..
      /* acceptable missing combinations are thus
	 0-2, 0-3, 0-4
	 1-2, 1-3, 1-4
	 2-3, 2-4, 3-4
	 i.e. a total of 9 unique ones.. 0-1 is not possible
       */

      double sheepall = pow(eff,4);
      double sheep3 = 3*pow(eff,3)*(1-eff); // any one of the first 3 can be missing

      double result4 = pow( (all + rest4), 4);
      double result3 = pow( (all + rest4 + rest3), 4);

      double resultsheep = pow( (sheepall + sheep3),4);

      cout << " eff " << eff
	   << " all " << all 
	   << " rest4 " << rest4 
	   << " rest3 " << rest3 
	   << " result4 " << result4 
	   << " result3 " << result3 
	   << " resultsheep " << resultsheep 
	   << endl;

      h3->Fill(eff, result3);
      h4->Fill(eff, result4);
    }

  // draw
  h3->GetXaxis()->SetTitle("MUID 2-pack eff.");
  h3->SetLineColor(4);
  h3->SetMarkerColor(4);
  h3->SetMarkerStyle(3);
  h4->SetLineColor(2);
  h4->SetMarkerColor(2);
  h4->SetMarkerStyle(30);

  h3->Draw("p");
  h4->Draw("p same");

  TLegend *leg = new TLegend(0.6,0.2,0.8,0.4);
  leg->AddEntry("h3","3 out of 5","p");
  leg->AddEntry("h4","4 out of 5","p");
  leg->Draw();

  c1->Modified();
  c1->SaveAs("muidll1eff.gif");

  h3->Clone("h3_clone");
  h3_clone->SetTitle("Eff. diff: for 3 - 4");
  h3_clone->Add(h4,-1);
  h3_clone->SetLineColor(1);
  h3_clone->GetXaxis()->SetTitle("MUID 2-pack eff.");
  h3_clone->Draw();
  c1->SaveAs("muidll1eff_diff.gif");
}