RRR
R−{(2n+1)π2;n∈z}R-\left\{\frac{(2 n+1) \pi}{2} ; n \in z\right\}R−{2(2n+1)π;n∈z}
[0,∞][0, \infty][0,∞]
(−∞,∞)(-\infty, \infty)(−∞,∞)
