Basic Hypergeometric Series - Watson's Contour Integral

Watson's Contour Integral

As an analogue of the Barnes integral for the hypergeometric series, Watson showed that

{}_2\phi_1(a,b;c;q,z) = \frac{-1}{2\pi i}\frac{(a,b;q)_\infty}{(q,c;q)_\infty} \int_{-i\infty}^{i\infty}\frac{(qq^s,cq^s;q)_\infty}{(aq^s,bq^s;q)_\infty}\frac{\pi(-z)^s}{\sin \pi s}ds

where the poles of lie to the left of the contour and the remaining poles lie to the right. There is a similar contour integral for r+1φr. This contour integral gives an analytic continuation of the basic hypergeometric function in z.

Read more about this topic:  Basic Hypergeometric Series

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