## table of contents

RINT(3) | Linux Programmer's Manual | RINT(3) |

# NAME¶

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

# SYNOPSIS¶

#include <math.h>

double nearbyint(doublex);float nearbyintf(floatx);long double nearbyintl(long doublex);

double rint(doublex);float rintf(floatx);long double rintl(long doublex);

Link with *-lm*.

**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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

**rintf**(), **rintl**():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

# DESCRIPTION¶

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.

# 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.

# ATTRIBUTES¶

For an explanation of the terms used in this section, see attributes(7).

Interface |
Attribute |
Value |

nearbyint (), nearbyintf (), nearbyintl (), rint (), rintf (), rintl () | Thread safety | MT-Safe |

# CONFORMING TO¶

C99, POSIX.1-2001, POSIX.1-2008.

# 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¶

# COLOPHON¶

This page is part of release 5.13 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/.

2021-03-22 |