Hi,
root 3.3.09
I have a set of files all with the same trees in (a t_cse and a t_filter).
Here is what happens:
root [0] TChain* ch_ce = new TChain("t_cse")
root [1] ch_ce->Add("./f*.root")
(Int_t)11
root [2] ch_ce->Draw("run:snarl", "projs==1")
<TCanvas::MakeDefCanvas>: created default TCanvas with name c1
(Int_t)20
root [3] ch_ce->Draw("run:snarl", "projs==1")
(Int_t)21
root [4]
you see that I run the same Draw command twice, but the first time it
selects 20 events and the second time it selects 21 events!, This really
worries me if I execute the same bit of code twice I get different
results. This effect seems to scale with files, and in the total data set
the difference is more than a factor of 2!!!. This isnt any fancy tree is
just a bog standard tree with bog standard Int_t and Float_t entries.
Exactly the same thing happens for TChain::Scan.
(the files I used to do this are at
http://www.hep.phy.cam.ac.uk/~howcroft/data_trees.tar.gz)
I'm using root 3.03/09 on redhat 7.3, gcc v3.0, i685.
Am I doing somthing really stupid?
Caius
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CAIUS HOWCROFT
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