[LCP]Rounding questions

[Chuck Martin]

On Thu, Sep 05, 2002 at 01:18:30PM +0300, Andrew Weaver wrote:
> Still cannot find a man entry on "round" though so not sur what it means.

Here's a rendered copy from Slackware 8.1:


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);

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  inte-
       ger like rint().

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.

NOTES
       POSIX  1003.1-2001  contains  text  about  overflow (which
       might set errno to ERANGE, or  raise  an  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  man-
       tissa  bits.   For the IEEE-754 standard 32-bit and 64-bit
       floating point numbers the maximum value of  the  exponent
       is 128 (resp. 1024), and the number of mantissa bits is 24
       (resp. 53).)

CONFORMING TO
       C99.

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



                            2001-05-31                   ROUND(3)

-------
Chuck