Hi,
I am doing a likelhood fit to a histogram as shown below. I noticed that whenever the fit is "FROM HESSE" I always see status of the fit 0. Is it expected?
( I do some similar fit with some other function in the same code and there I see correct status output when fit failed but there the fit result is "FROM MIGRAD". )
==fit is performed like this:
TFitResultPtr r=histo1->Fit(fNominal,“LSR”,"",minXFit,maxXFit); //here fNominal is fit function
cout<<"Status fit = "<Status()<<endl;
== fit status is always 0
FCN=0 FROM HESSE STATUS=FAILED 11 CALLS 103 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 -6.98403e+14 1.19490e+07 -6.95089e+14 0.00000e+00
2 p1 1.61005e+00 1.00000e+00 2.56121e-01 0.00000e+00
3 p2 1.71694e+01 1.00000e+00 4.07797e+00 0.00000e+00
4 p3 8.58925e+00 1.00000e+00 1.25124e+00 0.00000e+00
ERR DEF= 0.5
Status fit = 0
==Some other fit with correct status code but from MIGRAD:
FCN=0 FROM MIGRAD STATUS=FAILED 165 CALLS 166 TOTAL
EDM=-nan STRATEGY= 1 ERROR MATRIX UNCERTAINTY 100.0 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 -2.18902e-01 8.21951e-05 -nan 9.72032e+07
2 p1 4.89117e-02 nan -nan -nan
3 p2 7.40008e+00 1.00000e+00 -nan 0.00000e+00
ERR DEF= 0.5
Status fit = 4
Thanks
Regards,sushil