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():
           _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
       rint():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       rintf(), rintl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 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(), │ Thread safety │ MT-Safe │
       │nearbyintl(), rint(),      │               │         │
       │rintf(), rintl()           │               │         │
       └───────────────────────────┴───────────────┴─────────┘

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

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

COLOPHON

       This  page  is  part  of  release  5.10  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/.

                                                   2017-09-15                                            RINT(3)