====== ATN() ======

//Since version 2.0//

Syntax:

  atn%(<float expression>)
  
The ''ATN()'' function returns the arc tangent value of the given numeric expression. The function only accepts a float as its single argument and can only return a float.

Example:

  print atn%(1.0) * 4.0
  rem -- the above outputs 3.1415266