RINT(3)                   (2017-09-15)                    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():
              _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 accor-
          dance 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.

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     RINT(3)                   (2017-09-15)                    RINT(3)

          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).     allbox;    lbw26    lb    lb   l   l   l.
          Interface Attribute Value T{ nearbyint(), nearbyintf(),
          nearbyintl(), rint(),
          rintf(), rintl() T}   Thread safety  MT-Safe

     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 excep-
          tion).  In practice, the result cannot overflow on any  cur-
          rent 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/.

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