[Rivet] Thoughts on a Rivet 2.2.2 release?

[Chris Pollard]

Hey,

Yes, I agree. But I also think that YODA does need a physics-agnostic
> merging utility... or at least some merging helper functions.
> Unfortunately there's no way to tell if scale() is being called for
> normalization or some other purpose, so maybe that is an impossible goal.
>

Yeah, that's why I think it's perfectly alright to ask the user to give the
script some information about how histograms should be summed correctly.

What does ROOT's hadd utility do? I expect that it has exactly the same
> problems but for some reason I never hear anyone complaining! (At least
> not *this * aspect: I submitted some serious bugfixes many years ago and
> I know Holger recently had some trouble with it.) If the name is
> accurate, maybe it just adds histos/weights and ignores normalization?
> And for TGraphs?
>

If I'm not mistaken, hadd just sums the content of each bin and sums the
uncertainty on each bin in quadrature. I don't think ROOT histograms "know"
if they've been normalized or not, so there's no way for hadd to take this
into account. I don't think it even attempts to combine TGraphs.

Chris
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