Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.arch
Subject: Re: Comparison operators (was: He's not the only one at it again!)
Message-ID: <58995@lanl.gov>
Date: 2 Aug 90 22:36:31 GMT
References: <2377@crdos1.crd.ge.COM>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 19

From article <2377@crdos1.crd.ge.COM>, by davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr):
> [...]
>   When I generated a tiny implementation language I went back to := to
> avoid typing mistakes, and used <> instead of != because a lot more
> people could read it first time.

Well, you've actually got back to a comp.arch topic.  The problem here
is that <> doesn't mean the same thing as !=.  The first means (intuitively
anyway) less-than or greater-than, while the second means not equal.
Now, suppose you have two NANs:

      NAN1 <> NAN2
      NAN1 != NAN2

The first of these conditions is false whicl the second is true.  NANs
are unordered (so they can't be "less-than or greater-than" each other),
but they also always compare as "not equal".

J. Giles