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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