[ROOT] TH1::AddBinContent() and TH1::Sumw2()

From: Hadjidakis Cynthia (hadjida@ipno.in2p3.fr)
Date: Fri Mar 02 2001 - 18:08:09 MET 

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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