Hello rooters,
I am using ROOT 3.02/03 CVS as of Nov.12 on LINUX Mandrake.
I have a class that inherits from a TH2F. If I try to subtract
two of these historgrams, I get an empty histogram. To do the subtraction,
I use TH1::Add(TH1 *h1, TH1 *h2, Double_t c1, Double_t c2), with
c1=1,c2=-1. Obvious enough.
But I notice that fEntries is zero for this. According to TH1.h,
fEntries is the number of entries in the histogram. I assume that
this is different than the number of bins. Looking at
TH1::Fill(Axis_t x, Stat_t w) and TH2::Fill(Axis_t x, Axis_t y, Stat_t w)
I see the fEntries is incremented only once. I get a different fEntries
if I call TH1::Fill(x,1) N times vs. TH1::Fill(X,N).
Is this a bug or a feature??
--
RAINMAN
"How much does a piece of gum cost Ray?"
"About $100."
"How much does a new car cost Ray?"
"`Bout $100."
"There goes working for NASA!"
==================================================================
Ray Fliller: rfliller@bnl.gov Office Phone: (631)-344-6124
C-A Accelerator Physics Dept. Fax: (631)-344-5954
Building 911B
Brookhaven National Lab
Upton, NY 11973 Office: Room 211
http://www.agsrhichome.bnl.gov/People/rfliller/
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