Taylor Campbell wrote:
> It is defined for the sake of computational convenience;

Fine, but it *is* defined. Originally you stated that a NaN "represents
the condition of a computation whose meaning is undefined; it's not a
defined result."

There are many different arithmetics. Examples of integer arithmetic
that have been mentioned here are conventional arithmetic, modular
arithmetic, and saturated arithmetic. IEEE flonum arithmetic is a
further arithmetic; it may be strange, but it is (largely) well defined.

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México