Non Linear Least Square Fit with GSL MultiFit

Hi,

now I am back with new problems.

I have expanded the my script to the case of simultaneously fitting two equal model functions which have 3 parameters each of which they have 1 in common.

I oriented myself on the example another user has posted here
[url]Simultaneous hist fit; ROOT::Math::IMultiGenFunction trouble

This was of great help since it is my plan to make the script applicable for an arbitrary number of equal model functions of which all share 1 common parameter which is what I tried to do.

I can compile the script and everything works so far just not the fitting.
The error message I get is:

GSLNLSMinimizer: Invalid function set - only Chi2Func supported
Error in ROOT::Math::GSLNLSMinimizer::Minimize: Function has not been set
Error: Empty FitResult !

For me it is not clear why this happens since everything is very similar to the tutorial
http://root.cern.ch/root/html/tutorials/fit/combinedFit.C.html

Could you please have a look on my code one more time? I think you could directly see where I am going wrong.

I attached my code and the two necessary files for fitting.

Best regards,
Chris
fit_mass_table_beta_6_qmass_0.03_tc_WL.dat (561 Bytes)
fit_mass_table_beta_6_qmass_0.03_tc_Pion.dat (565 Bytes)
TestCombFit.C (7.05 KB)