ROUND(3) Linux Programmer's Manual ROUND(3)
NAME
round, roundf, roundl  round to nearest integer, away from zero
SYNOPSIS
#include <<math.h>>
double round(double x);
float roundf(float x);
long double roundl(long double x);
Link with lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
round(), roundf(), roundl(): _XOPEN_SOURCE >= 600  _ISOC99_SOURCE; or
cc std=c99
DESCRIPTION
These functions round x to the nearest integer, but round halfway cases
away from zero (regardless of the current rounding direction), instead
of to the nearest even integer like rint(3).
RETURN VALUE
The rounded integer value. If x is integral or infinite, x itself is
returned.
ERRORS
No errors other than EDOM and ERANGE can occur. If x is NaN, then NaN
is returned and errno may be set to EDOM.
CONFORMING TO
C99.
NOTES
POSIX.12001 contains text about overflow (which might set errno to
ERANGE, or raise an exception). In practice, the result cannot over
flow on any current machine, so this errorhandling stuff is just non
sense. (More precisely, overflow can happen only when the maximum
value of the exponent is smaller than the number of mantissa bits. For
the IEEE754 standard 32bit and 64bit floating point numbers the max
imum value of the exponent is 128 (respectively, 1024), and the number
of mantissa bits is 24 (respectively, 53).)
SEE ALSO
ceil(3), floor(3), lround(3), nearbyint(3), rint(3), trunc(3)
COLOPHON
This page is part of release 3.05 of the Linux manpages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/manpages/.
20070726 ROUND(3)
