Page 1 Next

Displaying 1 – 20 of 38

Showing per page

On a class of starlike functions defined in a halfplane

G. Dimkov, J. Stankiewicz, Z. Stankiewicz (1991)

Annales Polonici Mathematici

Let D = z: Re z < 0 and let S*(D) be the class of univalent functions normalized by the conditions l i m D z ( f ( z ) - z ) = a , a a finite complex number, 0 ∉ f(D), and mapping D onto a domain f(D) starlike with respect to the exterior point w = 0. Some estimates for |f(z)| in the class S*(D) are derived. An integral formula for f is also given.

On a modification of the Poisson integral operator

Dariusz Partyka (2011)

Annales UMCS, Mathematica

Given a quasisymmetric automorphism γ of the unit circle T we define and study a modification Pγ of the classical Poisson integral operator in the case of the unit disk D. The modification is done by means of the generalized Fourier coefficients of γ. For a Lebesgue's integrable complex-valued function f on T, Pγ[f] is a complex-valued harmonic function in D and it coincides with the classical Poisson integral of f provided γ is the identity mapping on T. Our considerations are motivated by the...

On bounded univalent functions that omit two given values

Dimitrios Betsakos (1999)

Colloquium Mathematicae

Let a,b ∈ z: 0<|z|<1 and let S(a,b) be the class of all univalent functions f that map the unit disk into {a,bwith f(0)=0. We study the problem of maximizing |f’(0)| among all f ∈ S(a,b). Using the method of extremal metric we show that there exists a unique extremal function which maps onto a simply connnected domain D 0 bounded by the union of the closures of the critical trajectories of a certain quadratic differential. If a<0

On local injectivity and asymptotic linearity of quasiregular mappings

V. Gutlyanskiĭ, O. Martio, V. Ryazanov, M. Vuorinen (1998)

Studia Mathematica

It is shown that the approximate continuity of the dilatation matrix of a quasiregular mapping f at x 0 implies the local injectivity and the asymptotic linearity of f at x 0 . Sufficient conditions for l o g | f ( x ) - f ( x 0 ) | to behave asymptotically as l o g | x - x 0 | are given. Some global injectivity results are derived.

Currently displaying 1 – 20 of 38

Page 1 Next