& sign()
 
  Syntax: sign(<number>)
 
  Returns -1, 0, or 1 depending on whether its argument is negative, 
  zero, or positive (respectively).
 
  Example:
  > say sign(-4)                                                                     
  You say "-1"
  > say sign(4)
  You say "1"
  > say sign(0)
  You say "0"
  > say sign(-1)
  You say "-1"