D[ArcTan[x, y], {y, \[Alpha]}] == (I/2) (1/(Sqrt[1/x^2] x) - 1) ((Log[-y] - Log[y])/ (y^\[Alpha] Gamma[1 - \[Alpha]])) + ((2^(-1 + \[Alpha]) Sqrt[Pi] y^(1 - \[Alpha]))/x) HypergeometricPFQRegularized[{1/2, 1, 1}, {1 - \[Alpha]/2, 3/2 - \[Alpha]/2}, -(y^2/x^2)] /; Abs[y] < Abs[x] && Element[y, Reals]

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2001-10-29