void riempi4() {

  TH1F histo("pippo","Numeri casuali",100,0.,1.);

  int num= 10000;
  for (int i = 0; i<num;++i) {
    //float rnd=gRandom->Rndm();
    float rnd=gRandom->Gaus(0.5,0.05);
    //float rnd=gRandom->Poisson(4.);
    histo.Fill(rnd);
  }

  gStyle->SetOptStat(111111);
  gStyle->SetOptFit(111111);
  histo.SetMinimum(0);

  histo.Fit("gaus");
  histo.DrawCopy();

  TF1* gaus = (TF1*)( histo.GetFunction("gaus"));
  cout << gaus << endl;

  float mean = gaus->GetParameter(1);
  float meanErr = gaus->GetParError(1);
  cout << "mean " << mean << "+/-" << meanErr<< endl;


  // TF1 pippo("pp","pol2",0.35,0.65);

  // histo.Fit("pp","R");
  // //histo.Fit("pol2");

  // //(histo.GetFunction("pp"))->Draw();
  // histo.DrawCopy("hist");
  // histo.DrawCopy("func same");
  //pippo.Draw();
  cout << histo.GetRMS() << endl;
  cout << "under " <<histo.GetBinContent(0) << endl;
  cout << "over " << histo.GetBinContent(histo.GetNbinsX()+1) << endl;

}