lispdoc - results for signum

(signum number)
Function: If NUMBER is zero, return NUMBER, else return (/ NUMBER (ABS NUMBER)).
Example:
(defun final-value (player board)
  "Is this a win, loss, or draw for player?"
  (case (signum (count-difference player board))
    (-1 losing-value)
    (0 0)
    (1 winning-value)))
Mentioned in:
CLtL2 - 12.5.2. Trigonometric and Related Functions
HyperSpec - Function SIGNUM
On Lisp - How Macros Work