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Re: expt weirdness in floatfns.c
From: |
Luc Teirlinck |
Subject: |
Re: expt weirdness in floatfns.c |
Date: |
Sat, 6 Aug 2005 18:43:08 -0500 (CDT) |
Richard Stallman wrote:
The comment suggests this was for compatibility with Common Lisp.
We may as well not change it.
I do not see how Emacs can be compatible with Common Lisp in this
respect, since it does not implement rational numbers. From the CL Hyperspec:
expt returns base-number raised to the power power-number. If the
base-number is a rational and power-number is an integer, the
calculation is exact and the result will be of type rational;
otherwise a floating-point approximation might result.
>From the Common Lisp implementation CLISP:
[1]> (expt 2 -2)
1/4
which is consistent with the above quote.
To be compatible with CL, Emacs should return 1/4, which it can not
do, having no rational numbers. 0.25, even though inexact, would
appear to be more "compatible" with 1/4 than 0.
Sincerely,
Luc.
Re: expt weirdness in floatfns.c,
Luc Teirlinck <=