Paul Sephton's article "A Question Of Rounding" in the Linux Gazette

[Vincent Lefevre <vincent@xxxxxxxxxx>]

Hi,

Most of you probably aren't aware of Paul Sephton's article
"A Question Of Rounding" in the Linux Gazette:

  http://linuxgazette.net/143/TWDT.html#sephton

As you can see, most of this article is wrong. Despite a few
complaints[*], the Linux Gazette editor doesn't want to remove
it. If the editor gets a few more complaints from you, perhaps
it will help to get it removed. The editor's e-mail address is
editor [at] linuxgazette.net.

If you don't have the time to read the article, here's a paragraph
from it (note: Paul Sephton is using the double precision, not a
decimal arithmetic):

  Whilst a number might be inexactly stored at a precision of 15
  decimals, that same number is exact when viewed at 14 decimals of
  precision. For example, the value 2.49999999999992 is promoted
  (using IEEE rounding) to 2.4999999999999 and then to 2.5 (with
  precision of 14) using the same rounding rules.

[*] from contributors of a (non-existent) bug reported by Paul Sephton:

  http://sourceware.org/bugzilla/show_bug.cgi?id=4943

-- 
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.org/>
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Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)