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INF vs 1/0
- To: Morrison@UTAH-20
- Subject: INF vs 1/0
- From: CSVAX.fateman at Berkeley
- Date: Thu, 18 Mar 1982 18:05:00 -0000
- Cc: common-lisp@su-ai
Basically, reading and writing these guys either way is no big deal.
There are representations of infinity in several floating point formats
(IEEE single, double, extended), which are printed as #[s INF] etc.
in the simple read/print package I have. #[r INF] would be consistent,
though eliminating some of the syntax (the CL manual does not have the
 stuff) may make numeric type info hard to determine. I do not like
to use unbounded lookahead scanners. (Think about reading an atom which
looks like a 2000 digit bignum, but then turns out to be something else
on the 2001th character).
Undefined numeric objects ("Not A Number") in the IEEE stuff, is much
stickier. Presumably there is some information encoded in the number
that should be presented (e.g. how the object was produced.)