W^3
Posts:
29
Registered:
4/19/11


Re: Elementary complex analysis
Posted:
Mar 8, 2013 4:00 PM


Another proof: Let f(z) = sum(n=0,oo) a_nz^n. Then f(1/z) = sum(n=0,oo) a_n/z^n. Now f(1/z) > oo as z > 0. Hence by CasatoriWeierstrass, f(1/z) has a pole at 0. Thus f(1/z) = sum(n=0,N) a_n/z^n => f(z) = sum(n=0,N) a_nz^n.

