Available Fitting functions

I was trying to find which are the available fitting functions apart from the “trivial” ones landau, expo, gaus, polN that is.
Searching through, I came accross this http://root.cern.ch/root/html/tutorials/fit/fit1.C.html
As I can tell, the function sqroot, is somehow loaded inside the code lines.
I also lookied in the user’s guide but only the aforementioned functions are reffered. I want to use a “power” fit a function like y=ax^b.

I know that I can probably create it on my own, but is there a “library” with all the available fitting functions?
Thank you very much in advance!

See the description of the TFormula class, its TFormula::Analyze method description and the various available methods in the TMath class.
P.S. Please note that in the majority of cases you yourself need to initialize parameters before invoking the “Fit” function (search for “Setting initial conditions” in the TH1::Fit and/or the TGraph::Fit methods description).

Thank you very much!!!
I’ll take a look at your links!!!