Re: TF1::Fit
Rene Brun (Rene.Brun@cern.ch)
Mon, 11 Jan 1999 14:17:20 +0100
Faouzi Attallah wrote:
>
> Hi Rooters,
>
> I am fitting a histogram hyds with a gaussian according to :
>
> g = new TF1("g","gaus",gmin, gmax);
> hyds->Fit("g","ER0");
> g->GetParameters(par);
> hyds->Draw() ;
>
> I got the following on my root-command-screen
>
> FCN=66.6685 FROM MINOS STATUS=PROBLEMS 1282 CALLS 1694
> TOTAL
> EDM=2.55251e-05 STRATEGY= 2 ERROR MATRIX
> ACCURATE
> EXT PARAMETER PARABOLIC MINOS ERRORS
> NO. NAME VALUE ERROR NEGATIVE POSITIVE
> 1 Constant 1.47776e+02 4.41311e+00 -3.80487e+00 3.80193e+00
> 2 Mean -2.83708e-04 3.83873e-04 -3.99915e-04 3.99098e-04
> 3 Sigma 1.52598e-02 2.16818e-06
>
> but on the graphics an information-window is appearing with the
> hist- parameters (I do believe) not the fit ones :
>
> hyds
> Nent = 1600
> Mean = -0.00539024
> RMS = 0.14343
>
> is it a bug ?
>
> Faouzi
No, you must activate the display of the fit parameters.
You have two solutions:
1- select item "Fit parameters" in teh canvas "Option" menu
2- gStyle->SetOptFit(); //see doc in this routine for options
Rene Brun