[ROOT] NAN in NTuples

From: mbrustke@purdue.edu
Date: Wed Jul 09 2003 - 22:23:56 MEST


I've read about some similar problems in the digest, but most of them seemed to 
involve histogramming, while mine simply involves accessing the values of 
leaves of a tree.  I setup a tree using the following syntax:
afile = new TFile("mc.root")
TTree *tt = afile.Get("t")
Unfortunately, my MC files are around 60 megs each, so I can't attach one.  I 
am working on creating a smaller file with a few good events and one or two bad 
ones, but I'm still a novice with root.  The problem happens with different 
instances of different variables, but the first one on which I noticed it was 
event #1431 of a variable called jetdata.ijet_phi.  When I call
tt->Scan("jetdata.ijet_phi")
all values display properly, but if I call
tt->FindLeaf("jetdata.ijet_phi")->GetValue(1431)
I get:
Error: Symbol nan is not defined in current scope  FILE: LINE:0
(const Double_t)nan
*** Interpreter error recovered ***
I have experienced this under versions 3.03/07, 3.03/09, and 3.05/03., all 
under various versions of Linux.  As I said, tt->Scan displays reasonable 
looking values for the offending variables, and I can histogram them without 
error, but accessing certain ones individually results in nan.  Even if there 
is no way to fix this, is there some way I can detect nan entries and simply 
skip them when I am looping over the entire dataset?

Thanks,
Max Brustkern



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