gMinuit?

ROOT
1

Hi,

I’d like to limit the number of iterations (to somehow avoid endless fitting) and used to use (in a CINT script)

gMinuit->SetMaxIterations(10);

with older ROOT versions. This doesn’t seem to work anymore (the problem is, that gMinuit==0; I already tried gSystem->Load(“libMinuit”))

So how can I do this now, or is there a smarter solution?
Is this also appropriate for compiled scripts?

Thank you very much in advance,
Klaus

2

Hello,

if you are using TMinuit directly, you need first to create an instance of the TMinuit class, by doing :

gMinuit = new TMinuit(npar);

where npar is the number of parameters used by Minuit.
See for example the tutorial Ifit.C :

root.cern.ch/root/html/examples/Ifit.C.html

Regards,

Lorenzo

3

Hi,
Maybe I misread Klaus’ post, but I think he’s asking how to set the max iterations when you do something like

myHistPtr->Fit("gaus");

not when you roll your own.

(Even if that’s not what he wanted, I want to know, so… :smiley: )

Cheers,
Charles

4

If this is the case, then you do not need to use gMinuit,
it is enough to do before calling TH1::Fit:

TVirtualFitter::SetMaxIterations(maxiter);

Lorenzo