Hi! I have a problem using TChain and TTree::AddFriend together. ROOT version is 3.03/09: ----------------------------------------------------------------------------- // create the main tree: TFile h("Run0001.Physics.Header.root"); TTree *t = (TTree *)h.Get("Physics"); t->Draw("Counter.Physics"); // <--- Works TChain *c = new TChain("Tracker"); c->Add("Run0001.Physics.Tracker.Raw*.root"); // <--- Adds 11 files, 1MB each c->Draw("Unpacked.NChannels"); // <-- Works t->AddFriend(c, "Tracker"); t->Draw("Tracker.Unpacked.NChannels"); // *** Break *** segmentation violation ----------------------------------------------------------------------------- The last line gives a segfault. If I open just the first file of the chain (or put all events into one file without chains), it works: ----------------------------------------------------------------------------- TFile f("Run0001.Physics.Tracker.Raw.root"); TTree *c = (TTree*)f.Get("Tracker"); c->Draw("Unpacked.NChannels"); // <-- Works t->AddFriend(c, "Tracker"); t->Draw("Tracker.Unpacked.NChannels"); // <-- Works ----------------------------------------------------------------------------- It also works if the chain uses only one file (removing the "*" in the first code snippet). Adding the second file gives the error, but already at the first event. Is this a bug in ROOT or can't I just add TChains as friends to other trees? Ole
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