A function giving the arc tangent of its argument in radians. The permitted range of the argument is from - to + infinity.
By convention, the result will be in the range -PI/2 to +PI/2 (-90 to +90 degrees).
If you know the tangent of the angle, this function will tell you the angle (in radians).
As the magnitude of the argument (tangent) becomes very large (approaches + or - infinity) the accuracy diminishes.
In the example below, radian_angle becomes equal to the angle (in radians) whose tangent is y.
radian_angle=ATN(y)
You can convert the answer to degrees by using the DEG function. (The DEG function is equivalent to multiplying by 180/PI.) The example below is similar to the first one, but the angle is in degrees.
degree_angle=DEG(ATN(y))
Syntax
<n-var>=ATN(<numeric>)