rint(3) - Linux manual page (original) (raw)

rint(3) Library Functions Manual rint(3)

NAME top

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

LIBRARY top

   Math library (_libm_, _-lm_)

SYNOPSIS top

   **#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_**);**

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 <= 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 top

   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)](../man3/fesetround.3.html)) 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)](../man3/fetestexcept.3.html)) when the result differs in value from the
   argument.

RETURN VALUE top

   These functions return the rounded integer value.

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

ERRORS top

   No errors occur.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **nearbyint**(), **nearbyintf**(),           │ Thread safety │ MT-Safe │
   │ **nearbyintl**(), **rint**(), **rintf**(),       │               │         │
   │ **rintl**()                              │               │         │
   └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

   C11, POSIX.1-2008.

HISTORY top

   C99, POSIX.1-2001.

   SUSv2 and POSIX.1-2001 contain text about overflow (which might
   set _[errno](../man3/errno.3.html)_ to **ERANGE**, or raise an **FE_OVERFLOW** exception).  In
   practice, the result cannot overflow on any current machine, so
   this error-handling stuff was 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).)  This was removed in POSIX.1-2008.

   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)](../man3/lrint.3.html)
   instead.

SEE ALSO top

   [ceil(3)](../man3/ceil.3.html), [floor(3)](../man3/floor.3.html), [lrint(3)](../man3/lrint.3.html), [round(3)](../man3/round.3.html), [trunc(3)](../man3/trunc.3.html)

COLOPHON top

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   man-pages@man7.org

Linux man-pages 6.10 2024-07-23 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), roundup(3), trunc(3)