### NAME

nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to nearest integer

### SYNOPSIS

**#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 || _ISOC99_SOURCE; or
*cc -std=c99* **rint**(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or
*cc -std=c99* **rintf**(), **rintl**(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or
*cc -std=c99*

### DESCRIPTION

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.

### RETURN VALUE

These functions return the rounded integer value.

If *x* is integral, +0, -0, NaN, or infinite,
*x* itself is returned.

### ERRORS

No errors occur. POSIX.1-2001 documents a range error for overflows, but see NOTES.

### CONFORMING TO

C99, POSIX.1-2001.

### NOTES

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.

### SEE ALSO

ceil(3), floor(3), lrint(3), round(3), trunc(3)

### COLOPHON

This page is part of release 3.23 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/.