TH1 with assymetric poissonnian error bars

ROOT
1

Dear Support,

Is there a way to set or/and compute assymetric poissonian error bar for each bin of a TH1F histogram?
Because TH1::SetBinError() seems to take only a single error as argument. And plot with the “E” option draw symetric bars.

Thanks by advance,
Guillaume Blanc

2

Guillaume,

Use a TGraphAsymmErrors class.
With the current version in CVS, you can automatically create a TGraphAsymmErrors object from a TH1 object.

Rene