# $EPIC: atan.txt,v 1.3 2006/08/21 01:55:33 sthalik Exp $
Returns the principal value in radians of the arc tangent of <number>.
If the <number> argument is omitted the empty string is returned.
As always, the return value is limited to 6 decimal places.
As always, DOM or RANGE means there was an error.
The arc tangent of an angle