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libelec
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Homework Statement
Find and classify the singularities in C* of [tex]f(z) = \frac{{\pi z - \pi {z^3}}}{{\sin (\pi z)}}[/tex], and give information about Res(f, 0) and Res(f, infinity)
The Attempt at a Solution
I found that the singularities in C are z = n, with n [tex]\in[/tex] Z, n[tex]\neq[/tex] 0, n[tex]\neq[/tex] 1. These are simple poles, while z=0 and z=1 are removable singularities (therefore, Res(f, 0)=0).
Now, in C*: what I thought is that, since the poles tend to infinity when n tends to infinity, then there is a non-isolated singularity.
But then I don't know how to calculate Res(f, infinity).
Did I think that the right way or what am I missing?
Thanks.
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