Re: 2dim fitting

Faouzi Attallah (attallah@gsi.de)
Sat, 1 May 1999 10:53:35 +0200 (CED)


On Fri, 30 Apr 1999, Markus Weiss wrote:

> Hi,
>
> I like to fit a function of two values f(x,y) with 3 parameters
> to datapoints of
>
> x1, y1, f1
> x2, y2, f2
> ....
>
> I tried the ntuple-class, and TF2 for the usersupplied function,
> but seem not to get the desired result. Basically I'm lost...
>
> Has anyone solved this rather simple problem ?
>
> Thanks, Markus.
>
> --
> ---------------------------------------------------------------------
> Markus Weiss "Ah elbereth glithoniel
> BESSY-2 Projektteam silvren penna miriel"
> e-mail: weiss@abbe.exp.bessy.de phone: +49-30-6392-2941
> ---------------------------------------------------------------------
>

Hi Markus,

I hope Rene agrees with the following syntaxe. In the 2dim-hist case and
a usersupplied function as, e.g. a 2dim Polynome of 1st degre one can
write:

TH2F *Hr ; // the 2-dim host
...
pol = new TF2 ("pol","[0]*x + [1]*y + [2]", xmin, xmax, ymin, ymax) ;
pol->SetParNames("Ax","Ay","B") ;
hr->Fit("pol","R0") ;

Cheers,
Faouzi

F. Attallah GSI mbH Planckstr 1 D-64291 Darmstadt
Tel: +49 (0)6159 71 2743
Fax: +49 (0)6159 71 2901
Email: F.Attallah@gsi.de