Arcus Tangens

Function

definiendum $\arctan: \{z\in\mathbb C\mid |z|\le 1, z\neq \pm i\}\to\mathbb C$
definiendum $\arctan(z):=\sum_{n=0}^\infty (-1)^n\frac{1}{2n+1} z^{2n+1} $

Theorems

$\frac{{\mathrm d}}{{\mathrm d}z}\arctan(z)=\frac{1}{1+z^2}$

References

Wikipedia: Inverse trigonometric functions


Exponential function