Kumar, D.; Kasana, H. S. Maximum modulus, maximum term and approximation error of an entire harmonic function in \(R^3\). (English) Zbl 0927.30018 Riv. Mat. Univ. Parma (6) 1, 215-223 (1998). For any function \(h\), harmonic on \(\mathbb R^3\), let \(E_{n}(h,R)\) denote the infimum of the supremum norm \(\| h-g\| _{B(R)}\), where \(g\) is a harmonic polynomial of degree \(\leq n\) and \(B(R)\subset\mathbb R^3\) denotes the Euclidean ball of radius \(R\). The authors present estimates of \(E_{n}(h,R)\) for some classes of entire harmonic functions. Reviewer: M.Jarnicki (Kraków) MSC: 30D15 Special classes of entire functions of one complex variable and growth estimates 41A30 Approximation by other special function classes PDFBibTeX XMLCite \textit{D. Kumar} and \textit{H. S. Kasana}, Riv. Mat. Univ. Parma (6) 1, 215--223 (1998; Zbl 0927.30018) Full Text: Link