rint(3) — Linux manual page

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(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

       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.

ATTRIBUTES

       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()                             │               │         │
       └─────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       C99, POSIX.1-2001.

       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 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)
       instead.

SEE ALSO

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

COLOPHON

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Linux man-pages 6.9.1          2024-06-16                        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)

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