{
  delete gRandom;
  gRandom = new TRandom(123456) ;
  TH1F *hist = new TH1F("hist", "Gauss Distribution", 200, 0, 20);
  for(int i=0; i<1000; ++i) {
    double a=gRandom->Gaus(10,2) ;
    hist->Fill(a) ;
  }
  c1=new TCanvas("c1", "Gauss", 600, 400);
  c1->cd();
  hist->Draw() ;
}