Fitting problem using RooAddPdf model

ROOT
1

Dear ROOTers

i’m using RooFit from root version 5.15/04 and fitting
a resonance signal plus an exponential background,
I use a model made with RooAddPdf, sum of signal RooVoigtian and
background RooExponential, both extended with proper yelds:

 // signal
  RooVoigtian signal("signal","Breit Wigner plus Resol Model",m,M,Gamma,sigma);	
  RooExtendPdf signalE("signalE","Breit Wigner plus Resol (ext)",signal,Ns);
  // background	
  RooExponential back("back","Exponential background Model",m,c);
  RooExtendPdf backE("backE","Exponential background Model (ext)",back,Nb);
  // model
  RooAddPdf model("model","signal+bg",RooArgList(signalE,backE),RooArgList(Ns,Nb));

and then fit with:

model.fitTo(DATA_MuonSpecN1,Extended(),Range(60000,120000),Minos(kFALSE),Save(kTRUE),PrintLevel(-1));

i get a lot of lines like

RooAbsRealLValue::inFitRange(m): value 33281.2 rounded up to min limit 60000
RooAbsRealLValue::inFitRange(m): value 34218.8 rounded up to min limit 60000
RooAbsRealLValue::inFitRange(m): value 35156.2 rounded up to min limit 60000
RooAbsRealLValue::inFitRange(m): value 36093.8 rounded up to min limit 60000
RooAbsRealLValue::inFitRange(m): value 37031.2 rounded up to min limit 60000

which are apparently without end.
Is this normal ? They seems to be related with the fit range imposed ( i get similar lines for superior limit). They disappear if no limit is imposed or if i
fit with a RooExtendPdf with fit limits.
Can you help me with this ?

Many thanks,
Max.

2

I have notified Wouter Verkerke of your problem. I hope that he will reply soon.

Rene

3

Hi Max,

That doesn’t look normal.

Can you send me a self-contained working example macro of your fit?

Then I’ll figure out what the problem is.

Wouter

4

Hi Wouter,
you can take this

~mbellomo/public/example.C

from lxplus.
There are lines like:

//******** change ******//
//signalE.fitTo(DATA_MuonSpecN1,Extended(),Range(60000,120000),Minos(kFALSE),Save(kTRUE));
model.fitTo(DATA_MuonSpecN1,Extended(),Range(60000,120000),Minos(kFALSE),Save(kTRUE));
//**********************//

where changing comments from signalE (RooExtendPdf) to model (RooAddPdf) you can test each behaviour.
Note that if you remove the Range limits with model fit, also this works.
Thanks,
Max

5

any news ?