calculator thinks 12!! = 0

calculator thinks 12!! = 0

[Joe Wells]

Dear Emacs gurus,

To reproduce the problem, type "M-x calculator RET 12 ! !".  You will
see the result "0".

More reasonable behavior would be what calculator does on 171!, which
is return "inf".

Additional strange behavior can be found by calculating 11!!, which
seems to run forever (or at least longer than I had the patience to
wait).

The same poor behaviors can be observed also in Emacs 21.4 with the
"-q" command line option, so this is not a new bug and it does not
appear to depend on my configuration.

Joe

----------------------------------------------------------------------
In GNU Emacs 22.1.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2007-06-27 on artemis
Windowing system distributor `The X.Org Foundation', version 11.0.70000000
configured using `configure  '--prefix=/home/jbw/local2' '--enable-debug' '--disable-nls' '--with-x-toolkit=gtk' 'CFLAGS=-O0 -g3 -ggdb''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: jbw
  value of $LANG: nil
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Re: calculator thinks 12!! = 0

[Eli Barzilay]

Joe Wells <jbw@macs.hw.ac.uk> writes:

> Dear Emacs gurus,
> 
> To reproduce the problem, type "M-x calculator RET 12 ! !".  You will
> see the result "0".
> 
> More reasonable behavior would be what calculator does on 171!, which
> is return "inf".
> 
> Additional strange behavior can be found by calculating 11!!, which
> seems to run forever (or at least longer than I had the patience to
> wait).
> 
> The same poor behaviors can be observed also in Emacs 21.4 with the
> "-q" command line option, so this is not a new bug and it does not
> appear to depend on my configuration.

The calculator's factorial is nothing too sophisticated...  It was
mostly a proof of concept.  Some of the things that you see are a
result of what you get with:

  (truncate 479001600.0)

(the calculator catches the error and uses 0 instead).  I have a fix
for that -- if someone tells me where to send a new version to, I'll
do that so it gets in.

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

Re: calculator thinks 12!! = 0

[Eli Zaretskii]

> From: Eli Barzilay <eli@barzilay.org>
> Date: 02 Jul 2007 21:35:47 -0400
> 
> I have a fix for that -- if someone tells me where to send a new
> version to, I'll do that so it gets in.

Please send it to emacs-devel@gnu.org.  Thanks.

Re: calculator thinks 12!! = 0

[Richard Stallman]

    (the calculator catches the error and uses 0 instead).  I have a fix
    for that -- if someone tells me where to send a new version to, I'll
    do that so it gets in.

If you have a patch for Emacs, please send the diff -c
together with an itemized change log entry
to emacs-devel@gnu.org.