est integer

       #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 ||
           or cc -std=c99
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
           _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

       The nearbyint(), nearbyintf(), and nearbyintl() functions  round  their
       argument  to  an integer value in floating-point format, using the cur-
       rent 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.

       These functions return the rounded integer value.

       If x is integral, +0, -0, NaN, or infinite, x itself is returned.

       No  errors  occur.  POSIX.1-2001 documents a range error for overflows,
       but see NOTES.

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

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

       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

                                  2013-08-26                           RINT(3)
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