Hello ROOTers!
I have a histogram which is the ratio of two correlated histograms.
I used TH1F::Divide(TH1 *h1, TH1 *h2, Double_t c1, Double_t c2, Option_t
*option); with option="B" to get the resulting distribution with binomial
errors. But it seems that calculated errors are not binomial.
Example below illustrates this problem.
Am I doing something wrong?
Mikhail
PS
I use
* Version 2.25/03 15 September 2000 *
CINT/ROOT C/C++ Interpreter version 5.14.50, Sep 2 2000
{
gROOT->Reset();
c1 = new TCanvas("c1","The FillRandom example",200,10,700,900);
gaus1 = new TFormula("gaus1","gaus");
gaus1->SetParameters(1000,10,1);
h1f = new TH1F("h1f","Test random numbers",200,0,20);
h1f->FillRandom("gaus1",10000);
TH1F *bindistr = new TH1F("binomial","Test binomial",200,0,20);
bindistr->Divide(h1f,h1f,1.0,2.0,"B");
/*
Int_t nbinsx = h1f->GetNbinsX();
Double_t w, n2;
for (Int_t binx=0; binx<=nbinsx+1; binx++)
{
w = bindistr->GetBinContent(binx);
n2 = h1f->GetBinContent(binx);
if (n2)
bindistr->SetBinError(binx,sqrt(w*(1-w)/n2));
else
bindistr ->SetBinError(binx,0.0);
};
*/
bindistr->Draw("E");
c1->Update();
}
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