Dear experts,
It seems there is a bug in ROOT::Fit::FitResult::Chi2() method in root versions 6-30-01, 6-30-02.
To show it, I am attaching the tutorial combinedFit.C with one additional line
cout<<" Chi2 = "<<result.Chi2()<<endl;
The output is:
Processing combinedFit.C...
****************************************
Minimizer is Minuit2 / Migrad
MinFCN = 131.104
NDf = 115
Edm = 2.11602e-08
NCalls = 225
Par_0 = 5.5396 +/- 0.0354094
Par_1 = 4.66089 +/- 0.050106
Par_2 = -0.0514037 +/- 0.00108539 (limited)
Par_3 = 77.2733 +/- 3.93105 (limited)
Par_4 = 30 (fixed)
Par_5 = 4.864 +/- 0.243005
Chi2 = -1
You can see, that result.Chi2() returns -1 while it returns the correct value 131.104 in older root versions.
combinedFit.C (4.0 KB)