X axis errors and fit procedure

Hello,
I have a question on the fit procedure when fitting an histogram:
(I just use h->Fit(“f1”,“R”), where h is my TH1F and f1 is a user defined function)
How does the uncertainties on the x axis enter into the fit procedure? Does the fit procedure consider an uncertancy on the x axis when I fit an histogram? And, if yes, how is it calculated?

Thanks in advance
Paola

When fitting an histogram the uncertainty in x is not taken into account because an histogram represent normally a frequency (or density) of a sampled distribution.
If you want to fix a set of x[] and y[] measurements with their errors you should use the class TGraphErrors

root.cern.ch/root/htmldoc/TGraphErrors.html

and the TGraph::Fit() method:

root.cern.ch/root/htmldoc/TGraph.html#TGraph:Fit

which takes into account the error in x

Best Regards

Lorenzo