I have a problem with use of TFractionFitter::Fit
Data visually fits good, but the result of method fit->GetChisquare() is negative
MIGRAD TERMINATED WITHOUT CONVERGENCE.
FCN=-1.97054e+08 FROM MIGRAD STATUS=FAILED 759 CALLS 760 TOTAL
EDM=443949 STRATEGY= 1 ERR MATRIX NOT POS-DEF
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 frac0 1.44484e-03 1.13388e-01 -0.00000e+00 1.48446e+01
2 frac1 1.57449e-02 2.75460e-02 0.00000e+00 9.89670e+02
3 frac2 1.64246e-03 1.17819e-01 0.00000e+00 -1.49871e+00
4 frac3 1.98203e-02 2.38820e-02 0.00000e+00 9.84011e+03
5 frac4 9.20691e-01 1.60204e-01 0.00000e+00 -2.48712e+00
6 frac5 6.63541e-02 5.06279e-04 -0.00000e+00 8.82979e+02
7 frac6 2.30875e-03 2.37152e-02 0.00000e+00 4.03144e+02
8 frac7 5.94077e-04 5.24383e-02 0.00000e+00 -2.89598e+03
9 frac8 3.14295e-02 1.51803e-02 -0.00000e+00 6.38966e+03
10 frac9 6.87188e-06 1.19117e-01 0.00000e+00 -5.49713e+00
11 frac10 3.45691e-04 5.27233e-05 -0.00000e+00 9.54741e+03
ERR DEF= 0.5
Warning in TFractionFitter::Fit: Abnormal termination of minimization.
fit status: 4
My output:
Chi-square: -2608.75
NDF: 1185
Prob: 0
_ROOT Version:6.22/00
_Platform:linux