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 || _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

DESCRIPTION
       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.

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.

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  (respec-
       tively, 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 3.25 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/.



                                                           2008-08-05                                                    RINT(3)