Inverse Tangent

First off, I know the tangent function is math.tan.
What I want to achieve with it is if I do this

math.tan( math.rad ( 23 ) ) --Returns the tangent of 23 in degrees

and get 0.4244748162096 what is the inverse tangent function that will turn 0.4244748162096 back into 23.

[lua]math.deg( math.atan( num ) )[/lua]

Works perfectly, Thanks!

Turns out I had to use radians all along.