{
   auto c = new TCanvas("c","Marker sizes",0,0,500,200);
   TMarker marker;
   marker.SetMarkerStyle(3);
   Double_t x = 0;
   Double_t dx = 1/6.0;
   for (Int_t i=1; i<6; i++) {
      x += dx;
      marker.SetMarkerSize(i*0.2); marker.DrawMarker(x,.165);
      marker.SetMarkerSize(i*0.8); marker.DrawMarker(x,.495);
      marker.SetMarkerSize(i*1.0); marker.DrawMarker(x,.835);
   }
}