//  Example of a circular Tree
//  Circular Trees are interesting in online real time environments
//  to store the results of the last maxEntries events.
//  for more info, see TTree::SetCircular
// Author: Rene Brun
void circular() {
   gROOT->cd(); //make sure that the Tree is memory resident
   TTree *T = new TTree("T","test circular buffers");
   TRandom r;
   Float_t px,py,pz;
   Double_t random;
   UShort_t i;
   T->Branch("px",&px,"px/F");
   T->Branch("py",&py,"px/F");
   T->Branch("pz",&pz,"px/F");
   T->Branch("random",&random,"random/D");
   T->Branch("i",&i,"i/s");
   T->SetCircular(20); //keep a maximum of 20000 entries in memory
   for (i = 0; i < 65; i++) {
     //r.Rannor(px,py);
     //pz = px*px + py*py;
     px = py = pz = i;
     //random = r.Rndm();
     random = px + py + pz;
      T->Fill();
      cout<<i<<":"<<T->GetEntries()<<endl;
   }
   T->Print();
   T->SetBranchAddress("px",&px);
   T->SetBranchAddress("py",&py);
   T->SetBranchAddress("pz",&pz);
   T->SetBranchAddress("random",&random);

   unsigned int nentries = T->GetEntries();
   for(unsigned int j=0; j<nentries; j++){
     T->GetEntry(j);
     cout<<nentries<<":"<<j<<":"<<px<<":"<<py<<":"<<pz<<":"<<random<<endl;
   }

}