From 1f52771fd3ec79937626e7a3a71ad4427d07e31c Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Thu, 9 Jul 2020 08:40:17 -0700 Subject: [PATCH] Mention floating rounding issues * doc/lispref/numbers.texi (Float Basics): Mention floating-point rounding issues uncovered by the discussion in Bug#42417. --- doc/lispref/numbers.texi | 3 +++ 1 file changed, 3 insertions(+) diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi index 4002b36ce50..f018ef4c7c0 100644 --- a/doc/lispref/numbers.texi +++ b/doc/lispref/numbers.texi @@ -227,6 +227,9 @@ you are using. On all computers supported by Emacs, this is and is discussed further in David Goldberg's paper ``@url{https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html, What Every Computer Scientist Should Know About Floating-Point Arithmetic}''. +On modern platforms, floating-point operations follow the IEEE-754 +standard closely; however, results are not always rounded correctly on +some obsolescent platforms, notably 32-bit x86. The read syntax for floating-point numbers requires either a decimal point, an exponent, or both. Optional signs (@samp{+} or @samp{-}) -- 2.39.5