Hello,

But you don't have to worry oO

If you're not used to the cot function, you can substitute by cos/sin.

Singularities appear at points where the function is not defined, and whether it's cot or cos/sin, they're the same.

0 is obviously a singularity (not necessarily a pole because of sin(pi z))

So here, there are also singularities for any (the set of integers)