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       nearbyint,  nearbyintf,  nearbyintl,  rint,  rintf,  rintl  -  round to
       nearest 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 ||
       _ISOC99_SOURCE; or cc -std=c99
       rint(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
       _ISOC99_SOURCE; or cc -std=c99
       rintf(), rintl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
       || _ISOC99_SOURCE; or cc -std=c99


       The  nearbyint()  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() 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.


       C99, POSIX.1-2001.


       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.


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


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       be found at

                                  2008-08-05                           RINT(3)