Hi Cynthia,
Why are you calling AddBinContent and not Fill ?
TH1::Fill calls:
- AddBinContent
- increments the sum of squares of weights for the bin
see: http://root.cern.ch/root/html225/src/TH1.cxx.html#TH1:Fill
Rene Brun
Hadjidakis Cynthia wrote:
>
> Hi,
>
> I have a problem with filling my histogram with TH1::AddBincontent()
> combined with TH1::Sumw2() : my error bar is always null.
>
> TH1F *histo = new TH1F("histo","histo",10,0,10);
> histo->Sumw2();
> histo->AddBinContent(1,2);
> histo->AddBinContent(1,3);
>
> cout<<"error "<<histo->GetBinError(1)<<endl;
>
> It returns : error 0
>
> TH1::Sumw2() works perfectly with the TH1::Fill() method but not in this
> case.
> Does anybody know why ?
>
> Thanks,
>
> Cynthia
>
> ps : I work on the 2.25 ROOT version
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