Is there a big difference between TFitter and TMinuit?

Hello all.

@moneta I’m trying to appreciate if there is a big difference between the TFitter and TMinuit classes, and when one should be used over the other (or if one should always be used over the other?). I see from the documentation of TFitter that TFitter is based on TMinuit (see, so this suggests to me that TFitter is the newer class and should be used instead. Is this correct? Or is TFitter really the exact same as TMinuit, just acting as a “wrapper” that is more friendly to interact with?

Thank you in advance for any help.


TFitter is just a wrapper for TMinuit and it is a class that we do not recommend to use it. We have replaced the TFItter class with the ROOT::Fit::Fitter class since several years and we recommend to use that one for a complex fitting problem. With the new Fitter class you can also use different minimisers in addition to TMinuit


Okay, thank you for this explanation. I wasn’t aware of ROOT::Fit::Fitter. I didn’t see any tutorial code for this class but it’s possible that I missed it, can you please direct me to one if one exists?

You can look at


Okay, thank you very much!