Re: Fitting TGraphErrors

Hi,

  using option "F" in your particular case showed a problem. Thank you for your example.
This is now fixed in the trunk version and your macro works fine. What stated in the doc is correct, with the linear fitter error in X are not taken into account when fitting a TGraphErrors

  Best Regards

  Lorenzo
On Feb 24, 2009, at 1:25 PM, OKUMURA, Akira wrote:

> Hello Rene,
>
> Did you mention this?
> =======
> Note, that the linear fitter doesn't take into account the errors in
> x. If errors in x are important, go through minuit (use option "F"
> for polynomial fitting).
> =======
>
> I tried "F" option, but the result becomes chi^2/ndf = 0/0
>
> Regards,
>
> OKUMURA, Akira oxon_at_ceres.phys.s.u-tokyo.ac.jp
> Department of Physics, The University of Tokyo
> 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033
> TEL/FAX +81 3-5841-4173/4059
> Skype : okumura.akira
>
> On 2009/02/24, at 21:03, Rene Brun wrote:
>
>> see comments in the doc of TGraph::Fit
>> http://root.cern.ch/root/html/TGraph.html#TGraph:Fit
>>
>> Rene Brun
>>
>> OKUMURA, Akira wrote:
>>> Hello ROOTers,
>>>
>>> I attache an example of TGraphErrors::Fit. The left plot returns
>>> reasonable chi^2/ndf, but the right side doesn't. The result
>>> depends on the variable "kScale" in the macro.
>>>
>>> The fitting results from the left and the right plots should be
>>> the same value mathematically.
>>>
>>> Am I doing something incorrect?
>>>
>>> 5.22.00 + Mac OS X 10.5.6
>>>
>>> Regards,
>>>
>>> OKUMURA, Akira oxon_at_ceres.phys.s.u-tokyo.ac.jp
>>> Department of Physics, The University of Tokyo
>>> 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033
>>> TEL/FAX +81 3-5841-4173/4059
>>> Skype : okumura.akira
>>
>
Received on Tue Feb 24 2009 - 17:36:46 CET