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():
           _XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE;
           or cc -std=c99
       rint():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       rintf(), rintl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

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.

       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

   Multithreading (see pthreads(7))
       The nearbyint(), nearbyintf(), nearbyintl(), rint(), rintf(), and  rintl()  functions  are
       thread-safe.

CONFORMING TO

       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 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 3.54 of the Linux man-pages project.  A  description  of  the
       project,     and    information    about    reporting    bugs,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

                                            2013-08-26                                    RINT(3)