[Rivet] Rivet 1.5.0 now?

[Frank Siegert]

Hi Ben,

> Not that you asked me, but...

Heh, I did ask everybody on the list!

> Strictly speaking it is only the denominator that needs to be checked
> anyway, but I agree it makes more sense only to avoid dividing by zero,
> not to avoid negative values.

True, but in case the numerator is zero then I can ignore the division 
anyway and return the default 0, so it's at least not wrong.

> If you do change this, you will probably have to change some other
> methods to keep the behaviour consistent. For example, sumBinHeights
> also checks for a positive sum of weights.

Well, in this particular case I was not worried about negative sumw, but 
about negative sumyw, i.e. the underlying distribution being negative. 
If the sum of weights becomes negative one has to worry about more 
things, I agree, but I don't think there's actually a use case for that, 
is there? Certainly not something I'd like to change so close to the 
release.

Cheers,
Frank