Hi,
I found this post since I was trying to do the same.
In may case the “combined” fit is done more or less exactly how is done in
root.cern.ch/root/html/tutorials … Fit.C.html
and I also obtain the error about the absence of the model function.
For me is not so easy to modify my code following the prescriptions said here since really I was starting differently (with the struct as in the example and not with a class, and by the way I don’t find the documentation for FitFCN(int npars, pointer to struct, …).
I tried also to pass to FitResult the model via ROOT::Fit::Chi2Function::ModelFunction() but I’m not able since any object I try to pass or is const while a non-const is needed or, If I try to build a non-const one via the copy constructor I cannot since everything I try is a pure abstract class…
Where I’m wrong? Can somebody help me?
Thanks,
Matteo