Hi Patricia, Why do you call Sumw2 if you are happy with the sqrt(contents) ? Rene Brun On Tue, 28 Mar 2000, Patricia Fachini wrote: > Hi, > > I define my histograms as: > > typedef TH1D StHbt1DHisto; > mNumerator = new StHbt1DHisto(TitNum,theTitle,nbins,MinvLo,MinvHi); > mDenominator = new StHbt1DHisto(TitDen,theTitle,nbins,MinvLo,MinvHi); > mDifference = new StHbt1DHisto(TitDif,theTitle,nbins,MinvLo,MinvHi); > > mNumerator->Sumw2(); > mDenominator->Sumw2(); > mDifference->Sumw2(); > > mNumerator->Scale(1./NEvents); > mDenominator->Scale(1./NEvents); > mDifference->Scale(1./NEvents); > > and after running my macro: > > root4star [17] hh2->GetBinContent(50) > (Stat_t)8.04982038234593347e+02 > root4star [18] hh2->GetBinError(50) > (Stat_t)1.26884362824517383e+00 > > root4star [19] hhh2->GetBinContent(50) > (Stat_t)7.85032637287047692e+03 > root4star [20] hhh2->GetBinError(50) > (Stat_t)3.96240501355956098e+00 > > You see that the error in the bin is not the square root of the bin > contents, as I would expect... What am I missing here? > > Thank you, > Patricia > > __________________________________________________________________ > Patricia Fachini, Ph.D. 1-313-577-5419 -> WSU > Universidade de Sao Paulo 1-631-344-7635 -> BNL > Wayne State University pfachini@physics.wayne.edu > >
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