Re: definition of binomial error in histogram division?

Please read comments in the doc of TH1::Divide at http://root.cern.ch/root/htmldoc/src/TH1.cxx.html#hh46dE

When using the pro release 5.16 the error in bin1 is null.

Rene Brun

Suyong Choi wrote:
> Hi,
>
> In ROOT 5, the binomial error I expect to get with the "B" option in
> histogram
> division isn't the "standard" binomial error.
> What is its precise definition? If it's a bug it should be fixed,
> if it's not, the documentation should be updated.
>
> I attach an example where I expect to see an error of 0, but
> it's 0.0496 instead.
>
> Regards,
> Suyong
>
> ------------------------------------------------------------------------
>
> {
> TH1F *h1 = new TH1F("h1", "Demonimator", 1, 0.0, 1.0);
> TH1F *h2 = new TH1F("h2", "Numerator", 1, 0.0, 1.0);
>
> h1->Sumw2();
> h2->Sumw2();
>
> h1->Fill(0.5,10.0);
> h2->Fill(0.5,10.0);
>
> h1->Divide(h1, h2, 1.0, 1.0, "B");
> }
>
Received on Tue Jul 03 2007 - 17:16:45 CEST