From abba5c067d42e3ecf3ad018f8ae98f60ef1ca170 Mon Sep 17 00:00:00 2001 From: Tim Peters Date: Mon, 26 Jul 2004 05:12:01 +0000 Subject: Explain that most floats are actually integers. This is a common confusion for people using floor(), ceil() and modf(). --- Doc/lib/libmath.tex | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Doc/lib/libmath.tex b/Doc/lib/libmath.tex index 7f25eba..e52f8f9 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} -- cgit v0.12