trouble with trees

From: Peter Steinberg (steinber@nevis1.nevis.columbia.edu)
Date: Mon Apr 05 1999 - 22:10:25 MEST


Hello -

Now, I thought i knew how to make trees with variable length branches:

   Int_t nPhot;
   Float_t E[500];
   Float_t Px[500];
   Float_t Py[500];
   Float_t Pz[500];
   Float_t Arm[500];
   Float_t PhotProb[500];

   TTree* nEmcPhotons = new TTree("nEmcPhotons","EMC Photons");
   nEmcPhotons->Branch("nPhot",&nPhot,"nPhot/I");
   nEmcPhotons->Branch("E",E,"E[nPhot]/F");
   nEmcPhotons->Branch("Px",Px,"Px[nPhot]/F");
   nEmcPhotons->Branch("Py",Py,"Py[nPhot]/F");
   nEmcPhotons->Branch("Pz",Pz,"Pz[nPhot]/F");
   nEmcPhotons->Branch("Arm", Arm,"Arm[nPhot]/F");
   nEmcPhotons->Branch("PhotProb", PhotProb,"PhotProb[nPhot]/F");

now when i Fill() this tree and save it to a file and then try and read it
back
and Draw() any of the variable-length fields, i get:

root [0] TFile f("nEmcPhotons.root")
root [1] nEmcPhotons->Draw("Pz")
Warning in <MakeDefCanvas>: creating a default canvas with name c1
Warning in <TBranch::GetBasket>: Estimated keylen too small=15697
Fatal in <operator new>: storage exhausted
aborting

making bufsize=128000 in the Branch() calls does not help...

- Peter



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