Estimation of the best approximation of periodic functions of two variables by an "angle" in the metric of L p

被引：0
作者：
Kononovych T.O. [1 ]
机构：
[1] Poltava Pedagogic University, Poltava
来源：
Ukrainian Mathematical Journal | 2004年 / 56卷 / 9期
关键词：
Periodic Function; Fourier Coefficient; Trigonometric Series;
D O I：
10.1007/s11253-005-0124-8
中图分类号：
学科分类号：
摘要：
We obtain upper bounds in terms of Fourier coefficients for the best approximation by an "angle" and for norms in the metric of L p for functions of two variables defined by trigonometric series with coefficients such that Σ k1=0 ∞ Σ k2=0 ∞ (Σ l1=0 ∞ Σ l2=0 ∞ |Δ 12a l1l2|) p (k 1+1) p-2 (k 2+1) p-2) < ∞ for a certain p, 1 < p < ∞. © 2005 Springer Science+Business Media, Inc.
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页码：1403 / 1416
页数：13
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