Hi, thanks for the reply. However, it didn't work: I made the function fline.C, and then tried root [1] .L fline.C root [2] TF1 *fline = new TF1("fline",fline,30,180,2) ... make histogram... root [36] p0->Fit("fline","l") Error: class,struct,union or type $TF1 not defined Error: class,struct,union or type $TF1 not defined FILE:fline.C LINE:5 Error: No symbol TF1::RejectPoint() in current scope FILE:fline.C LINE:5 FCN=14024.8 FROM MIGRAD STATUS=CONVERGED 75 CALLS 76 TOTAL EDM=0 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 100.0 per cent EXT PARAMETER APPROXIMATE STEP FIRST NO. NAME VALUE ERROR SIZE DERIVATIVE 1 p0 0.00000e+00 1.41421e+00 0.00000e+00 0.00000e+00 2 p1 0.00000e+00 1.41421e+00 0.00000e+00 0.00000e+00 *** Interpreter error recovered *** Error: class,struct,union or type $TF1 not defined FILE:fline.C LINE:5 Error: No symbol TF1::RejectPoint() in current scope FILE:fline.C LINE:5 root [37] Thanks much, -y ---------- Dr. Yuri Gershtein, Physics, Brown University. Based at Fermilab. Tel: (630)-840-3784. Fax: (630)-840-8886 E-Mail: Gerstein@fnal.gov On Sat, 8 Jun 2002, Rene Brun wrote: > 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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