Hi Yuri,
An example exclude.C:
//file exclude.C
Double_t fline(Double_t *x, Double_t *par)
{
if (x[0] > 2.5 && x[0] < 3.5) {
TF1::RejectPoint();
return 0;
}
return par[0] + par[1]*x[0];
}
void exclude() {
TF1 *f1 = new TF1("f1","[0] +[1]*x +gaus(2)",0,5);
f1->SetParameters(6,-1,5,3,0.2);
TH1F *h = new TH1F("h","background + signal",100,0,5);
h->FillRandom("f1",2000);
TF1 *fline = new TF1("fline",fline,0,5,2);
fline->SetParameters(2,-1);
h->Fit("fline","l");
}
Rene Brun
On Sat, 8 Jun 2002, Yuri Gershtein wrote:
> Hi,
>
> so I have a peak which sits on a low statistics background, so
> I should use log likelihood.
> I want to fit just background without the peak, say with [1]*x+[0].
>
> Can I define a non-contiguos range for the fit?
> Setting errors to zero doesn't seem to work for the log likelihood (I
> think in PAW it used to work, i.e. non-zero bin with zero error was
> excluded from the fit).
>
> Also, in PAW I knew how to control the FCN calculation, and though this
> was not graceful, it worked...
>
> Thanks for your help,
> Yuri
>
>
> ----------
> Dr. Yuri Gershtein, Physics, Brown University.
> Based at Fermilab. Tel: (630)-840-3784. Fax: (630)-840-8886
> E-Mail: Gerstein@fnal.gov
>
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