[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: fix for expt bug
From: |
Ludovic Courtès |
Subject: |
Re: fix for expt bug |
Date: |
Thu, 04 Nov 2010 00:27:25 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
Hi Mark,
Mark H Weaver <address@hidden> writes:
> I just realized that there is a better way to fix these bugs. We don't
> need a new top-level case in expt after all. Instead, we generalize the
> scm_integer_expt case to support inexact integer exponents.
You mean “inexact number”, right?
The doc for ‘integer-expt’ makes the same mistake:
"Return @var{n} raised to the power @var{k}. @var{k} must be an\n"
"exact integer, @var{n} can be any number.\n"
However, an integer is necessarily an exact number, whereas the converse
isn’t true:
--8<---------------cut here---------------start------------->8---
scheme@(guile-user) [25]> (exact? 2/3)
$4 = #t
scheme@(guile-user) [25]> (integer? 2/3)
$5 = #f
--8<---------------cut here---------------end--------------->8---
In actuality, ‘integer-expt’ expects K to be an integer (fixnum or
bignum).
So I suspect that your patch doesn’t work because ‘inexact->exact’
returns something that’s obviously not necessarily an integer:
--8<---------------cut here---------------start------------->8---
scheme@(guile-user) [25]> (inexact->exact 2.3)
$6 = 2589569785738035/1125899906842624
--8<---------------cut here---------------end--------------->8---
Does that make sense?
Thanks,
Ludo’.
- Re: fix for expt bug, (continued)
- Re: fix for expt bug, Ramakrishnan Muthukrishnan, 2010/11/02
- Re: fix for expt bug, Mark H Weaver, 2010/11/02
- Re: fix for expt bug, Ludovic Courtès, 2010/11/02
- Re: fix for expt bug, Mark H Weaver, 2010/11/02
- Re: fix for expt bug, Ramakrishnan Muthukrishnan, 2010/11/03
- Re: fix for expt bug, Mark H Weaver, 2010/11/03
- Re: fix for expt bug, Ramakrishnan Muthukrishnan, 2010/11/03
- Re: fix for expt bug, Mark H Weaver, 2010/11/03
- Re: fix for expt bug, Ramakrishnan Muthukrishnan, 2010/11/03
- Re: fix for expt bug, Ramakrishnan Muthukrishnan, 2010/11/03
- Re: fix for expt bug,
Ludovic Courtès <=
- Re: fix for expt bug, Mark H Weaver, 2010/11/04
- Re: fix for expt bug, Ludovic Courtès, 2010/11/08
- Re: fix for expt bug, Andy Wingo, 2010/11/20
- Re: fix for expt bug, Ludovic Courtès, 2010/11/21
- [PATCH] Fix bugs in expt and integer-expt, Mark H Weaver, 2010/11/04
- Re: [PATCH] Fix bugs in expt and integer-expt, Ludovic Courtès, 2010/11/10