Non-real zeros of derivatives of real meromorphic functions

Langley, J.

doi:10.1090/S0002-9939-09-09979-1

Non-real zeros of derivatives of real meromorphic functions
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by J. K. Langley PDF

Proc. Amer. Math. Soc. 137 (2009), 3355-3367 Request permission

Abstract:

The main result of this paper determines all real meromorphic functions $f$ of finite order in the plane such that $f’$ has finitely many zeros while $f$ and $f^{(k)}$, for some $k \geq 2$, have finitely many non-real zeros.

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