Error propagation

ROOT
1

Hi,
I have two histograms a and b with corresponding errors e1 , e2. For my normalization i have to multiply “a” by 4 then add “b”:
b->Add(a,4)
when i ask b->Draw(“e”) the error is not propagated as Sqrt[ (4a)^2+b^2] but just Sqrt of the bin contents.
Any help please

2

Read documentation of TH1::Add (IMPORTANT NOTE)
root.cern.ch/root/html/TH1.html#TH1:Add

Rene