A remark on a modified Szász-Mirakjan operator
We prove that, for a sequence of positive numbers δ(n), if as , to guarantee that the modified Szász-Mirakjan operators converge to f(x) at every point, f must be identically zero.
A review of procedures for summing Kapteyn series in mathematical physics.
A survey of certain results on strong approximation by orthogonal series
This is a survey of results in a particular direction of the theory of strong approximation by orthogonal series, related mostly with author's contributions to the subject.
A survey of weighted polynomial approximation with exponential weights.
Algebraische Analysis [Book]
Chebyshev polynomials and some methods of approximation.
Density methods and results in approximation theory
Approximation theory and functional analysis share many common problems and points of contact. One of the areas of mutual interest is that of density results. In this paper we briefly survey various methods and results in this area starting from work of Weierstrass and Riesz, and extending to more recent times.
Müntz type theorems. I.
On the expansion of a function in terms of spherical harmonics in arbitrary dimensions.
On the theorem of Géza Grünwald and Józef Marcinkiewicz
This survey is a tribute to Géza Grünwald and Józef Marcinkiewicz dealing with the so called Grünwald-Marcinkiewicz Theorem.
Polynomial approximation and twenty years later.
Strong uniqueness.
The second order modulus again: some still (?) open problems.