TVirtualFitter and contour plots

ROOT
1

Hi,
I’m confused of what I should use to get countour plots.
I’m using in my macro TMinuit trought TVirtualFitter:
TVirtualFitter::SetDefaultFitter(“Minuit”);
TVirtualFitter * minuit = TVirtualFitter::Fitter(0,5);

Using
TGraph gr01 = (TGraph)minuit->Contour(40,0,1);
I have compilation error: ‘class TVirtualFitter’ has no member named ‘Contour’

and using

TGraph gr01 = (TGraph)Minuit->Contour(40,0,1);
gives this error:
Warning in TMinuit::Contour: Cannot find more than 4 points, no TGraph returned
also if the fit converges well (status ok and error matrix accurate)

What am I doing wrong?

Thanks,
Marianna.

2

Hi,
This is just my guess about your 2nd method (it seems to be correct: no compilation error):
Maybe the contour plot extends beyond the parameter ranges, so that Minuit is not able to compute it.
Try to set larger parameters ranges.

[quote=“testa”]Hi,
I’m confused of what I should use to get countour plots.
I’m using in my macro TMinuit trought TVirtualFitter:
TVirtualFitter::SetDefaultFitter(“Minuit”);
TVirtualFitter * minuit = TVirtualFitter::Fitter(0,5);

Using
TGraph gr01 = (TGraph)minuit->Contour(40,0,1);
I have compilation error: ‘class TVirtualFitter’ has no member named ‘Contour’

and using

TGraph gr01 = (TGraph)Minuit->Contour(40,0,1);
gives this error:
Warning in TMinuit::Contour: Cannot find more than 4 points, no TGraph returned
also if the fit converges well (status ok and error matrix accurate)

What am I doing wrong?

Thanks,
Marianna.[/quote]