ChebyshevU[\[Nu], z] == ((2^(-2 - \[Nu]) Sqrt[1 - z] (-1 + z)^\[Nu])/ Sqrt[-1 - z]) (1 + Sqrt[(1 + z)/(-1 + z)])^(2 \[Nu] + 2) - ((2^\[Nu] Sqrt[1 - z] (-1 + z)^(-2 - \[Nu]))/Sqrt[-1 - z]) (1 + Sqrt[(z + 1)/(z - 1)])^(-2 \[Nu] - 2) /; !IntervalMemberQ[Interval[{-1, 1}], z]

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2007-05-02