Fitting a function with 6 parameters

Roofit and RooStats
1

Hi
I am fitting a function with 6 parameters. The fit procedure gives me ;
FCN=37.3445 FROM HESSE STATUS=RESET 47 CALLS 172 TOTAL
EDM=7.36163e-13 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 50.0 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c 1.98425e+00 3.74147e-02 3.74147e-04 -1.31228e+02
2 q 1.00144e+00 9.52820e-04 9.52820e-06 -2.09618e+05
3 l 7.42506e+00 2.40283e+00 2.40283e-02 -8.33164e+01
4 nV 4.15052e+00 3.86363e-01 3.86363e-03 -5.12542e+02
5 nV0 -2.91115e-01 1.03034e-01 1.03034e-03 1.90513e+03
6 k 6.61930e+00 3.74341e-01 3.74341e-03 2.47397e+01

The error matrix is not correct; parameters are changing with input values.
I am attaching my code and data file. How to get the correct parameters !

Please help
Thanks and regards

2

Hi,

if the fit is not converging smoothly, there is no universal solution.
Perhaps the model is not adequate to the input data or the statistic is poor. In general it is hard to blame the fitting tool.

Danilo