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numbers, oh well.
- To: Richard Fateman <fateman%ucbdali@UCB-VAX.ARPA>
- Subject: numbers, oh well.
- From: "David A. Moon" <Moon@SCRC-RIVERSIDE.ARPA>
- Date: Thu, 4 Oct 84 20:30 EDT
- Cc: common-lisp@SU-AI.ARPA
- In-reply-to: <8410041709.AA00759@ucbdali.ARPA>
Date: Thu, 4 Oct 84 10:09:14 pdt
From: fateman%ucbdali@Berkeley (Richard Fateman)
"There are no infinities in the standard numbers of Common Lisp"
(this is repeated at the bottom of page 202 of aluminum edition.)
is inconsistent with the statement on p 19 of the same
edition, "... should approximate IEEE proposed standard ..." which
The first statement says that an implementation is not required to
provide infinities, and therefore portable programs cannot rely upon
infinite numbers. The second statement recommends that those
implementations that have a choice should approximate IEEE numbers in
their floating point, and thus some implementations are permitted and
even encouraged to have infinite floating point numbers. I fail to see
any inconsistency here.
Keeping 1/0 is probably less trouble than making it an error.
Floating point numbers and rational numbers are not the same.
Particular implementations of Common Lisp and the Common Lisp language
are not the same.
I think we've been through this discussion quite enough times before.
Let's work on something that matters.
For those of you who might think that arithmetic has been settled in a
correct and standard way in CL, I think that what has happened is that
people who have practical experience with error analysis and scientific
support have "tuned out" on CL, since it attempts to set a pseudo-standard
which is at odds with the IEEE (nearly adopted) standard.
I fail to find anything in the Common Lisp manual that forbids an implementation
to conform to the IEEE proposed standard. I fail to find anything in the Common
Lisp manual that requires me to change my machine, which currently conforms to
the IEEE proposed standard, and make it cease conforming to that standard.
Let's discuss something else.