Returns the trigonometric arc tangent (Atan), or inverse tangent, of a number.
Atan ( number )number - any numeric expression or field containing a numeric expression
number
FileMaker Pro 6.0 or earlier
The arc tangent is the angle, in radians, whose tangent is equal to the specified number.
Atan(1) returns .78539816....
Degrees(Atan(1)) returns 45.