Fit half-gaussian

Hi ROOTers,
maybe this is a FAQ but I would like to fit half a gaussian, that is a gaussian that has the mean on y-axis (x=0) and data only for x>0. I tried both automatically and with fit-panel with standard gaussian formula provided with “gaus” but this fails. Any ideas on how to do this? cheers,


using “gaus” should work if you set the range of the fit for x>0. Do:

h1->Fit("gaus","","",0, xmax);