Hi Mat, You have two options -option 1 t1->Draw("APHOE>>h1"); t1->Draw("BPHOE>>+h1"); // add to existing h1 -option 2 t1->Draw("APHOE>>h1"); t1->Draw("BPHOE>>h2"); TH1F *h1 = (TH1F*)gDirectory->Get("h1"); TH1F *h2 = (TH1F*)gDirectory->Get("h2"); h1->Add(h2); see doc of TTree::Draw, eg at: http://root.cern.ch/root/htmldoc/src/TTree.cxx.html#TTree:Draw Rene Brun On Fri, 9 Aug 2002, matthew dunseth wood wrote: > I am trying to add two histograms that I generated with TTree::Draw. The > commands I typed are as follows: > > TFile f("atlfast.root"); > TTree *t1 = (TTree*)f.Get("Atlfast/50"); > > t1->Draw("APHOE>>h1"); > t1->Draw("BPHOE>>h2"); > > h1->Add(h2); > > When I attempt to add the histograms I get the following: > > Error: Symbol h2 is not defined in current scope > FILE:/tmp/filewYtM0M_cint LINE:1 > *** Interpreter error recovered *** > > Why is h2 not defined in current scope? For that matter what is the > current scope? My knowledge of C++ is quite rudimentary so excuse me if > the answer to this is obvious. > > Matthew Wood > >
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