Approximation
We study the approximation of harmonic functions by means of harmonic polynomials in two-dimensional, bounded, star-shaped domains. Assuming that the functions possess analytic extensions to a δ-neighbourhood of the domain, we prove exponential convergence of the approximation error with respect to the degree of the approximating harmonic polynomial. All the constants appearing in the bounds are explicit and depend only on the shape-regularity of the domain and on δ. We apply the obtained estimates...
Let be a regular Jordan curve. In this work, the approximation properties of the -Faber-Laurent rational series expansions in the weighted Lebesgue spaces are studied. Under some restrictive conditions upon the weight functions the degree of this approximation by a th integral modulus of continuity in spaces is estimated.
give estimates for the approximation numbers of composition operators on the Hp spaces, 1 ≤ p < ∞
In the present paper, we study the polynomial approximation of entire functions of several complex variables. The characterizations of generalized order and generalized type of entire functions of slow growth have been obtained in terms of approximation and interpolation errors.