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Zeros of hypergeometric functions. (English) Zbl 1009.33004
Here it is shown that the hypergeometric function $$F(a,b;b+1;z)$$ has no zeros in a specified half-plane for certain ranges of parameters. It is also shown that the zeros of the hypergeometric polynomials $$F(-n,kn+ \ell+1; kn+ \ell+2;z)$$ cluster on one loop of a specified lemniscate. Other results then follow from quadratic relations.

##### MSC:
 33C05 Classical hypergeometric functions, $${}_2F_1$$ 30C15 Zeros of polynomials, rational functions, and other analytic functions of one complex variable (e.g., zeros of functions with bounded Dirichlet integral) 33C45 Orthogonal polynomials and functions of hypergeometric type (Jacobi, Laguerre, Hermite, Askey scheme, etc.)
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##### References:
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