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JOURNALS // Algebra i Analiz // Archive

Algebra i Analiz, 2024 Volume 36, Issue 5, Pages 163–172 (Mi aa1942)

Research Papers

Polynomial approximation in the mean on segments

N. A. Shirokov

St. Petersburg Department of Steklov Mathematical Institute of Russian Academy of Sciences

Abstract: Let $S_k$, $1\le k\le m$, be pairwise disjoint segments, $S_k = [a_k, b_k]$, $1\lt p_k\lt \infty$ functions $f_k$. Suppose that functions $f_k$ are defined on $S_k$, $f_k$ belongs to $C(S_k)$ and $f'_k$ belongs to $L^{P_k}(S_k)$. It is shown that for $n=1,2,\dots$ there are polynomials $P_n$, $ \deg P_n \le n$, that approximate all functions $f_k$ in the metric of $L^{P_k}$ with weights tending to infinity near the points $a_k$, $b_k$.

Keywords: polynomials, approximation in the mean, $L^p$ spaces.

Received: 22.04.2024


 English version:
St. Petersburg Mathematical Journal, 2025, 36:5, 755–761


© Steklov Math. Inst. of RAS, 2026