$$\lim_{x \to \infty}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = 2 \pi$$
$$\lim_{x \to 0^-}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = 0$$
More at x→0 from the left$$\lim_{x \to 0^+}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = 0$$
More at x→0 from the right$$\lim_{x \to 1^-}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = 4 \operatorname{atan}{\left(\frac{1}{2} \right)}$$
More at x→1 from the left$$\lim_{x \to 1^+}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = 4 \operatorname{atan}{\left(\frac{1}{2} \right)}$$
More at x→1 from the right$$\lim_{x \to -\infty}\left(4 \operatorname{atan}{\left(\frac{x}{2} \right)}\right) = - 2 \pi$$
More at x→-oo