| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
RINT(3) Linux Programmer's Manual RINT(3)
nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to nearest inte-
ger
#include <math.h>
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);
double rint(double x);
float rintf(float x);
long double rintl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
nearbyint(), nearbyintf(), nearbyintl():
_XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE;
or cc -std=c99
rint():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
rintf(), rintl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The nearbyint() functions round their argument to an integer value in
floating-point format, using the current rounding direction (see
fesetround(3)) and without raising the inexact exception.
The rint() functions do the same, but will raise the inexact exception
(FE_INEXACT, checkable via fetestexcept(3)) when the result differs in value
from the argument.
These functions return the rounded integer value.
If x is integral, +0, -0, NaN, or infinite, x itself is returned.
No errors occur. POSIX.1-2001 documents a range error for overflows, but see
NOTES.
C99, POSIX.1-2001.
SUSv2 and POSIX.1-2001 contain text about overflow (which might set errno to
ERANGE, or raise an FE_OVERFLOW exception). In practice, the result cannot
overflow on any current machine, so this error-handling stuff is just
nonsense. (More precisely, overflow can happen only when the maximum value of
the exponent is smaller than the number of mantissa bits. For the IEEE-754
standard 32-bit and 64-bit floating-point numbers the maximum value of the
exponent is 128 (respectively, 1024), and the number of mantissa bits is 24
(respectively, 53).)
If you want to store the rounded value in an integer type, you probably want
to use one of the functions described in lrint(3) instead.
ceil(3), floor(3), lrint(3), round(3), trunc(3)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
2010-09-20 RINT(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface