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

NAME

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

SYNOPSIS

       #include <math.h>

       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, see
       fenv(3)), instead of to the nearest even integer like rint(3).

       For example, round(0.5) is 1.0, and round(-0.5) is -1.0.

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.

VERSIONS

       These functions first appeared in glibc in version 2.1.

CONFORMING TO

       C99, POSIX.1-2001.

NOTES

       POSIX.1-2001 contains 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 num-
       bers 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 lround(3) instead.

SEE ALSO

       ceil(3), floor(3), lround(3), nearbyint(3), rint(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/.

								    2008-08-11								  ROUND(3)