(This message has been sent to comp.lang.ruby and is posted here just in case not everybody reaches it) In article <87puqk1tin.fsf_-_ / ev.netlab.co.jp>, Yukihiro Matsumoto <matz / netlab.co.jp> wrote: <snip> > |The reason people implement odd but not even is that odd is > |unambiguous, but people seem to disagree about whether zero is even. > > Really? I learned 0 is a even when I was in elementary school. > I thought it was a common sense. > > matz. "Andrew Hunt" <andy / Toolshed.Com> replied in Ruby-Talk: <snip> > But how would you expect zero to work? I believe that zero > is considered even (something like: "an integer n is called *even* if > there exists an integer m such that n = 2m", so 0 = (2)(0) is even). Actually, from my Calculus, I recall that 0 is not even considered a natural number... N = {1, 2, 3, 4, ...} # these are the natural numbers Z = {0, 1, -1, 2, -2, 3, -3, ...} # and these are the (real :) integers (actually Z = N U -N U {0}) and the definition of even number is 2N = { n E N / n%2 = 0 } which only applies to natural positive numbers... It's a matter of wholedness (no pun intended :), as when 0 enters into a definition, lots of definitions and tautologoes and theorems break... Regarding adding the method, for the sake of small interfaces, I'd say (n%2 == 1) is short enough and obvious enough to a programmer to be just enough (aliteration and repetition by accident :) just my E0.02 worth, d@ -- <excalibor at demasiado.com> <excalibor / my-deja.com> ------------------------------------------------------------- Mensaje enviado gracias al correo gratuito de Demasiado Corp. [ http://correo.demasiado.com ] -------------------------------------------------------------