On the partial sums of a Fourier series

被引:7
|
作者
Alzer, H. [1 ]
Koumandos, S. [1 ]
机构
[1] Univ Cyprus, Dept Math & Stat, CY-1678 Nicosia, Cyprus
关键词
trigonometric polynomials; inequalities;
D O I
10.1007/s00365-006-0665-0
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We give sharp lower estimates for the partial sums of the Fourier series sin x + cos2x/2 + sin3x/ 3 + cos4x/4 + ... , with both an even and odd number of terms. Our results are obtained through a monotonicity property of their local minima. In particular, we prove that all partial sums are positive on (0, pi).
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页码:253 / 268
页数:16
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