What is "LL" fitting option now doing?

I have recenlty run an old code on a new ROOT version. I do fitting with an “LL” option which is now, I think, replaced by a “WL” option. So… what “LL” option does now? Does it act like “L”? My fits results currenlty are very different and I am trying to find out what to do to reproduce results made with version 5.29 :slight_smile:

That’s an interesting issue.
The current ROOT “User’s Guide” (v5.26) mentions the “LL” option (but not the “WL” one) in the “Chapter 5. Fitting Histograms” in “The Fit Method” section:
while “LL” is not present (but “WL” is there) in the current (ROOT 5.30 and newer):
though “LL” is still present (but not the “WL”) in ROOT 5.28:

Just for the case something disappears completely one day: [quote]“LL” - An improved Log Likelihood fit in case of very low statistics and when bin contents are not integers. Do not use this option if bin contents are large (greater than 100).[/quote] [quote]“WL” - Use Loglikelihood method and bin contents are not integer, i.e. histogram is weighted (must have Sumw2() set)[/quote]
Some further explanations can be found in [url]Fitting histogram weighted with low stats “WL” option

Looking at my results I think it does the same what “WL” does, but I am not completely sure :slight_smile: