Hi Ahmet, The number of entries after an operation is most of the time meaningless unless you add two histograms where all weights had been set to 1. I do not see a reasonable and general solution to the number of entries in operations like subtraction, multiplication and division. What would you expect for: hdiff->Add(h2,h3,1.3,-1.6); In your case, you can do: Int_t N = h2->GetEntries() - h3->GetEntries(); hdiff->Add(h2,h3,1,-1); hdiff->SetEntries(N); if this has a meaning in your case. Rene Brun Ahmet Sedat Ayan wrote: > > Hi Rooters, > > I noticed that when I subtract two histograms as in the following > > TH1F *hdiff = new TH1F(*h1); > hdiff->Add(h2,h3,1,-1); > > the number of entries in the statistics box shows the sum of the number of > the entries of histos h2 and h3. Is this a bug? or? > > thankx > > ahmet > > *************** > > Ahmet Sedat Ayan > > Physics & Astronomy Dept. > Van Allen Hall > University of Iowa > Iowa City, IA, 52242 > > Voice : (++ 1 319) 335-2832 (W) (GMT-6) > Occupation : Ph.D Candidate (But still dreamer!) > e-mail : ayan@cms.physics.uiowa.edu > web : http://jazz.physics.uiowa.edu/~ayan
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