Re: [Gcl-devel] ansi-tests on a thinkpad & cetera

[Paul F. Dietz]

Camm Maguire wrote:

> My understanding is that the Common Lisp spec is silent on an
> implementation's treatment of Nan and Inf.  If so, and we are
> implicitly free to implement them in a useful way, I'd be happy to do
> so for maxima's benefit.  Paul, can we define NaN, and Inf as symbols
> with floating point constant values, and 1/0, -1/0, and 0/0 as
> analogous rationals?  What would be useful rules regarding expressions
> involving these symbols, beyond NaN - NaN = NaN et. al. mentioned
> above? 

The spec is indeed silent here, except to say that errors 'might' be signalled.
I am not an expert on floating point arithmetic, so I don't know what would
be most appropriate.  You probably want to consult ANSI/IEEE Std 754-1985
(IEEE Standard for Binary Floating-Point Arithmetic), which specifies
these in detail.  Also, look at what some other lisps do.

        Paul