4.3BSD-UWisc/man/cat3/floor.3m

FLOOR(3M)           UNIX Programmer's Manual            FLOOR(3M)



NAME
     fabs, floor, ceil, rint - absolute value, floor, ceiling,
     and round-to-nearest functions

SYNOPSIS
     #include <math.h>

     double floor(x)
     double x;

     double ceil(x)
     double x;

     double fabs(x)
     double x;

     double rint(x)
     double x;

DESCRIPTION
     Fabs returns the absolute value |x|.

     Floor returns the largest integer no greater than x.

     Ceil returns the smallest integer no less than x.

     Rint returns the integer (represented as a double precision
     number) nearest x in the direction of the prevailing round-
     ing mode.

NOTES
     On a VAX, rint(x) is equivalent to adding half to the magni-
     tude 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), ieee(3M), math(3M)





Printed 12/27/86          May 12, 1986                          1