rint(3) | Library Functions Manual | rint(3) |

# NAME

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

# LIBRARY

Math library (*libm*, *-lm*)

# 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);

**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 |

# STANDARDS

C11, POSIX.1-2008.

# HISTORY

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 127
(respectively, 1023), and the number of mantissa bits including the implicit
bit 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

2023-07-20 | Linux man-pages 6.05.01 |