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



NAME
       round, roundf, roundl - round to nearest integer, away from zero

SYNOPSIS
       #include <&lt;math.h>&gt;

       double round(double x);
       float roundf(float x);
       long double roundl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       round(), roundf(), roundl(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or
       cc -std=c99

DESCRIPTION
       These functions round x to the nearest integer, but round halfway cases
       away  from zero (regardless of the current rounding direction), instead
       of to the nearest even integer like rint(3).

RETURN VALUE
       The rounded integer value.  If x is integral or infinite, x  itself  is
       returned.

ERRORS
       No  errors other than EDOM and ERANGE can occur.  If x is NaN, then NaN
       is returned and errno may be set to EDOM.

CONFORMING TO
       C99.

NOTES
       POSIX.1-2001 contains text about overflow (which  might  set  errno  to
       ERANGE,  or  raise an exception).  In practice, the result cannot over-
       flow on any current machine, so this error-handling stuff is just  non-
       sense.   (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 max-
       imum value of the exponent is 128 (respectively, 1024), and the  number
       of mantissa bits is 24 (respectively, 53).)

SEE ALSO
       ceil(3), floor(3), lround(3), nearbyint(3), rint(3), trunc(3)

COLOPHON
       This  page  is  part of release 3.05 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/.



                                  2007-07-26                          ROUND(3)