@Carl Love 

Sorry for my mistakes and I have modified all errors in the topic now.

May I have more details about the question?

Like some part of process in maple. :)

Thanks so much.

@nm 

Thank you for you reply and that meaning is 

R₊ = {z : N^k(z) -> i as k -> ∞}; R_- = {z : N^k(z)  -> -i as k -> ∞}.