{
   auto c1   = new TCanvas("c1","c1",600,400);
   auto harr = new TH2F("harr","Option ARR + COLZ example",20,-4,4,20,-20,20);
   harr->SetStats(0);
   float px, py;
   for (Int_t i = 0; i < 25000; i++) {
      gRandom->Rannor(px,py);
      harr->Fill(px,5*py);
      harr->Fill(3+0.5*px,2*py-10.,0.1);
   }
   harr->Draw("ARR COLZ");
}