I want to perform a gaussian fit on TH2F histogram (lego plot). The top of the random gaussian distribution is cutted away (just a plateau around the center of the gaussian distrubion remains). Now I want to force root to take all bins into account for the fit except some specified bins at the center of the distribution.
So how can I force root to perfom a fit on a histogram without taking for example the bin content of bin  into account?
Thanks a lot for your help!