Comonotone approximation of twice differentiable periodic functions

• Datum: 2009
• Hauptverfasser: Dzyubenko, H. A., Дзюбенко, Г. А.
• Format: Artikel
• Sprache: Ukrainisch; Englisch
• Veröffentlicht: Institute of Mathematics, NAS of Ukraine 2009
• Online Zugang: https://umj.imath.kiev.ua/index.php/umj/article/view/3032
• Назва журналу: Ukrains’kyi Matematychnyi Zhurnal

In the case where a $2π$-periodic function $f$ is twice continuously differentiable on the real axis $ℝ$ and changes its monotonicity at different fixed points $y_i ∈ [− π, π), i = 1,…, 2s, s ∈ ℕ $(i.e., on $ℝ$, there exists a set $Y := {y_i } i∈ℤ$ of points $y_i = y_{i+2s} + 2π$ such that the funct...