Re: [ROOT] Errors used in TGraphErrors

From: Rene Brun (brun@pcbrun.cern.ch)
Date: Sun Aug 01 2004 - 19:40:29 MEST


see documentation of TGraph::Fit
http://root.cern.ch/root/htmldoc/TGraph.html#TGraph:Fit

Rene Brun

On Sun, 1 Aug 2004, 
Stilianos Kesisoglou 
wrote:

> Hi,
> 
> I was wondering, which is the method implemented for the assignment of
> errors in
> the TGraphErrors class? The above class accepts errors on both x and y, so
> how
> exaclty the errors are combined for the fit? I assume there is a chi^2
> function like:
> 
>              [ y-f(x) ]**2                     [ y-f(x) ]
>            ------------------       or        ( -------------- ) **2
>                  s**2                               s
> 
> What is the s in the above expressions? 
> 
> Thanks!
> 
> Stelios.
> 



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