On Thu, 14 Jun 2001, Antoine Cazes wrote:
>
> Dear Rooters,
>
> I cannot fit an histogram with a Breit Wigner. I created a function with
> two parameters ant fited the histogram:
>
> TF1 *bw = new TF1("bw","[0]/((x-[1])*(x-[1])+[0]/4)",0,1.4);
> h->Fit("bw");
>
> but the fit gives a line in the bottom of my plot and bad parameters.
>
> I also created a C++ function which initialize the TF1 object (like in
> the manual with the Lorenzian+background example (pages 66-67) but I get
> the same result.
>
> Then, I redefined the TF1 Object with 4 parameters:
>
> TF1 *bw = new TF1("bw","[0]/((x-[2])*(x-[3])+[1]/4)",0,1.4);
> h->Fit("bw");
>
> The fit look great in the screen, except that the parameters 0 and 1 or
> 2 and 3 are totally different.
>
> I use Root 3.0 on a Linux machine (RedHat 6.2)
>
> Thanks for your help,
>
> Antoine Cazes
>
> -------------------------------------
> Thomas Jefferson National Laboratory \
> Office 71 trailer 16 \ Institution: University of
> Phone: (757) 269 5551 \ South Carolina
> fax : (757) 269 6273 \
> http://www.jlab.org/~cazes/G7/ \
> --------------------------;-)
>
>
>
>
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