Re: Can not fit user function
Rene Brun (Rene.Brun@cern.ch)
Wed, 16 Jul 1997 16:22:54 +0200
Torsten Henkel wrote:
>
> Hi,
>
> I want to fit an user function to a profile histogram:
>
> [first part of the macro is sniped]
>
> h1->Draw("sm2:p>>smprof","side==1","profs");
> TF1 *fun2 = new TF1("fun2","[0]+[1]*pow(x,2)",3,10,2);
> fun2->SetParName(0,"const");
> fun2->SetParName(1,"sigma_b");
> fun2->SetParameter(0,0.03);
> fun2->SetParameter(1,0.003);
> smprof->Fit("fun2");
>
> [the rest also]
>
> I'm doing this in a macro, but all I get is a 'segmentation violation'.
> If i comment out the fit part it is working and making the histogram,
> but with it I get the error every time. I tried different names and
> functions but it's still the same. I'm running root version 1.01/07 on a
> Sparc 20.
> I hope anyone can help.
The TF1 class has several constructors.
In your case, you are calling a constructor with the wrong number
of parameters. If you do:
TF1 *fun2 = new TF1("fun2","[0]+[1]*pow(x,2)",3,10);
Your macro will be OK.
Rene Brun