RINT(3)                   386BSD Programmer's Manual                   RINT(3)

NAME
     rint - and round-to-closest integer functions

SYNOPSIS
     #include <math.h>

     double
     rint(double x)

DESCRIPTION
     The rint() function finds the integer (represented as a double precision
     number) nearest to x in the direction of the prevailing rounding mode.

NOTES
     On a VAX, rint(x) is equivalent to adding half to the magnitude and then
     rounding towards zero.

     In the default rounding mode, to nearest, on a machine that conforms to
     IEEE 754, rint(x) is the integer nearest x with the additional
     stipulation that if |rint(x)-x|=1/2 then rint(x) is even.  Other rounding
     modes can make rint() act like floor(), or like ceil(), or round towards
     zero.

     Another way to obtain an integer near x is to declare (in C)

           double x;     int k;    k = x;

     Most C compilers round x towards 0 to get the integer k, but some do
     otherwise.  If in doubt, use floor(), ceil(), or rint() first, whichever
     you intend.  Also note that, if x is larger than k can accommodate, the
     value of k and the presence or absence of an integer overflow are hard to
     predict.

SEE ALSO
     abs(3),  fabs(3),  ceil(3),  floor(3),  ieee(3),  math(3)

HISTORY
     A rint() function appeared in Version 6 AT&T UNIX.

BSD Experimental                  May 2, 1991                                1