[RF] Off-by-one error in Roofit/Histfactory/HistoToWorkspaceFactoryFast

[CoffeeIntoScience]

There is an error here that was introduced in dc65afe:

root/roofit/histfactory/src/HistoToWorkspaceFactoryFast.cxx

Lines 760 to 762 in 6abb8e9

	if (fObsNameVec.empty() || fObsNameVec.size() >= 3) {
	throw hf_exc("HistFactory is limited to 1- to 3-dimensional histograms.");
	}

This error should only be thrown when the number of observables is not 1, 2 or 3, but currently fires if the number is equal to 3.

See the change from dc65afe here where the mistake is evident:

dc65afe#diff-42ea09980f1ed2bacde4381f212c35d78be6ddedccf746953dc99d6455525d8aL1256-R1221

The conditional should be
if (fObsNameVec.empty() || fObsNameVec.size() > 3)

[guitargeek]

Thank you very much for reporting this!

I fixed this for the upcoming 6.30 and for the next patch releases 6.26.12 and 6.28.04 (this bug also affects 6.26).

The 6.28.04 patch release will probably come out this week.