Brief addition: Kahan and APL's 0/0 = 1

[sur-behoffski <sur_behoffski@...>]

Oops, sorry to (almost) reply to myself...

Just remembered that William Kahan noted that APL had chosen that the result
of dividing 0 by 0 would be 1, but that the language designers came to regret it:
Excerpted from the start of a DDJ article (November, 1997):

        DDJ: In addition to being a computer scientist, mathematician, and
             educator, you're also a researcher. What are your current
             interests?

        WK:  One of my areas of research is exception handling. My thesis is
             that exceptions are not errors unless they are handled badly.
             Exceptions are opportunities for extra computation.

        DDJ: Modern C and C++ agree with you.

        WK:  An exception is an event for which any policy you choose in
             advance will subsequently be found disadvantageous for somebody
             who will then, for good reason, take exception to the policy.

             Now, 3×6=18. That's not exceptional. Nobody's going to sue you.
             But what should we do with zero division?  The APL language took
             the approach that 0/0=1. Years later the guys who did it
             acknowledged, "If we knew then (in 1966), what we know now (1972),
             we wouldn't have done it."


http://ece621web.groups.et.byu.net/resources/FP/kahan-accuracy.pdf

cheers,

sur-behoffski