From: Tim Peters <tim.peters@gmail.com>
Date: Mon, 26 Jul 2004 05:12:01 +0000 (+0000)
Subject: Explain that most floats are actually integers.  This is a common confusion
X-Git-Tag: v2.4a2~141
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=abba5c067d42e3ecf3ad018f8ae98f60ef1ca170;p=python

Explain that most floats are actually integers.  This is a common confusion
for people using floor(), ceil() and modf().
---

diff --git a/Doc/lib/libmath.tex b/Doc/lib/libmath.tex
index 7f25eba675..e52f8f96fc 100644
--- a/Doc/lib/libmath.tex
+++ b/Doc/lib/libmath.tex
@@ -79,6 +79,14 @@ argument and return a pair of values, rather than returning their
 second return value through an `output parameter' (there is no such
 thing in Python).
 
+For the \function{ceil()}, \function{floor()}, and \function{modf()}
+functions, note that \emph{all} floating-point numbers of sufficiently
+large magnitude are exact integers.  Python floats typically carry no more
+than 53 bits of precision (the same as the platform C double type), in
+which case any float \var{x} with \code{abs(\var{x}) >= 2**52}
+necessarily has no fractional bits.
+
+
 Power and logarithmic functions:
 
 \begin{funcdesc}{exp}{x}