tsimplify problem

[AlexFekken]

Perhaps Parisse should not have said "complex" because (unlike e.g. exp) tan is already periodic on the real line, and so atan has real branches there, separated by multiples of pi.

So the "simplified" answer is correct, up to a multiple pi, which in my opinion is probably as much as you should expect when you are using variable arguments (as opposed to an explicit numerical argument that would allow you to obtain a "principal value").