arctan
The trigonometric arctangent function.
Syntax

arctan(x)

x
is a real or complex number

Description
For real values, arctan is the inverse of the restriction of the trigonometric tangent function to (−π/2, π/2); the domain is ℝ.
In general, arctan(z)
is defined as
arccos(z) = i/2 ⋅ [ln(1 − i⋅z) − ln(1 + i⋅z)]
where z
is a complex number.
Examples
arctan(√3)
1.0471975512 (=π/3)
arctan(−1)
−0.785398163397 (=−π/4)
4⋅arctan(1)
3.14159265359 (=π)
arctan(i/2)
0.549306144334⋅i