RINT(3)                             Linux Programmer's Manual                             RINT(3)



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 inte‐
       ger  value  in  floating-point  format,  using  the  current  rounding direction (see fes‐
       etround(3)) and without raising the inexact exception.

       The rint(), rintf(), and rintl() functions do the same, but will raise the inexact  excep‐
       tion (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 3.74 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 http://www.kernel.org/doc/man-pages/.



                                            2013-08-26                                    RINT(3)