Some inequalities for the Poincaré metric of plane domains
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- Sugawa, T. & Vuorinen, M. Math. Z. (2005) 250: 885. doi:10.1007/s00209-005-0782-0
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In this paper, the Poincaré (or hyperbolic) metric and the associated distance are investigated for a plane domain based on the detailed properties of those for the particular domain Open image in new window In particular, another proof of a recent result of Gardiner and Lakic  is given with explicit constant. This and some other constants in this paper involve particular values of complete elliptic integrals and related special functions. A concrete estimate for the hyperbolic distance near a boundary point is also given, from which refinements of Littlewood’s theorem are derived.