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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
RINT(3) Linux Programmer's Manual RINT(3)
nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to
nearest integer
#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():
_POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
rint():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
rintf(), rintl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
The nearbyint(), nearbyintf(), and nearbyintl() 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. When the current rounding direction is to
nearest, these functions round halfway cases to the even integer in
accordance with IEEE-754.
The rint(), rintf(), and rintl() 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.
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├───────────────────────────┼───────────────┼─────────┤
│nearbyint(), nearbyintf(), │ Thread safety │ MT-Safe │
│nearbyintl(), rint(), │ │ │
│rintf(), rintl() │ │ │
└───────────────────────────┴───────────────┴─────────┘
C99, POSIX.1-2001, POSIX.1-2008.
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 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2016-03-15 RINT(3)
Pages that refer to this page: abs(3), ceil(3), fabs(3), floor(3), lrint(3), lround(3), nextafter(3), nextup(3), round(3), trunc(3)