Copositive pointwise approximation

• Date: 1996
• Main Authors: Dzyubenko, H. A., Дзюбенко, Г. А.
• Format: Article
• Language: Russian; English
• Published: Institute of Mathematics, NAS of Ukraine 1996
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/5330
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

We prove that if a functionf ∈C (1) (I),I: = [−1, 1], changes its signs times (s ∈ ℕ) within the intervalI, then, for everyn > C, whereC is a constant which depends only on the set of points at which the function changes its sign, andk ∈ ℕ, there exists an algebraic polynomialP n =P n (x)...