G. Dzyubenko

activity

20152023

collaborators

4 papers

math.CA2023

Onesided, intertwining, positive and copositive polynomial approximation with interpolatory constraints

German Dzyubenko, Kirill A. Kopotun

Given $k \in N$ , a nonnegative function $f \in C^{r} [a, b]$ , $r \geq 0$ , an arbitrary finite collection of points ${α_{i}}_{i \in J} \subset [a, b]$ , and a corresponding collection…

math.CA2022

Degree of nearly comonotone approximation of periodic functions

German Dzyubenko

Let a $2 π$ -periodic function $f \in C$ changes its monotonicity at a finitely even number of points $y_{i}$ of the period. The degree of approximation of this $f$ by trigonometric…

math.CA2016

Jackson's type estimate of nearly coconvex approximation

German Dzyubenko

Suppose that a continuous on the real axis $2 π$ -periodic function $f$ changes its convexity at $2 s, s \in N,$ points $y_{i}$ on each period: $- π \leq y_{2 s} < y_{2 s - 1} < ... < y_{1} < π,$ an…

math.CA2015

One cubic 3-monotone spline

German Dzyubenko

For any 3-monotone on $[a, b]$ function $f$ (its third divided differences are nonnegative for all choices of four distinct points, or equivalently, $f$ has a convex derivative on $…