Re: [office-formula] Re: Excel's YEARFRAC algorithm

["David A. Wheeler" <dwheeler@dwheeler.com>]

Doug Mahugh:
> David,
> 
> I've finished testing and concluded that the VBA sample I had provided does indeed match Excel's behavior in all cases.

That's excellent news.  The Ruby story is interesting, but I don't think we need
to worry about it for now.

> So we can proceed on the basis that we know what Excel is doing, and your Python sample and my VBA sample both mirror Excel's actual YEARFRAC implementation accurately.

That _should_ be true. Of course, it's possible that none of the test cases exercise
a difference, though that seems improbable.

What I did is turn the Python code into an English spec, which SHOULD be the same.  There's a risk that this dropped something important, of course.  Care to take a look at the "Basis" section's English text and confirm that the definition is correct (at least for YEARFRAC, but really, we want it correct period)?

One oddity: The Excel code has special "Mode=3" handling that is quite odd - is that just dead code, or is it important for something?

--- David A. Wheeler