Some extremal problems in Lp(w)

被引:12
|
作者
Cheng, R
Miamee, AG
Pourahmadi, M
机构
[1] Univ Louisville, Dept Math, Louisville, KY 40292 USA
[2] Hampton Univ, Dept Math, Hampton, VA 23688 USA
[3] No Illinois Univ, Div Stat, De Kalb, IL 60115 USA
关键词
prediction error; outer function; dual extremal problem; stationary sequences;
D O I
10.1090/S0002-9939-98-04275-0
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Fix a positive integer n and 1 < p < infinity. We provide expressions for the weighted L-p distance [GRAPHICS] where d lambda is normalized Lebesgue measure on the unit circle, w is a nonnegative integrable function, and f ranges over the trigonometric polynomials with frequencies in S-1 = {...,-3,-2,-1} boolean OR {1,2,3,...,n}, S2 = {...,-3,-2,-1}\{-n}, or S3 = {...,-3,-2,-1} boolean OR {n}. These distances are related to other extremal problems, and are shown to be positive if and only if log w is integrable. In some cases they are expressed in terms of the series coefficients of the outer functions associated with w.
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页码:2333 / 2340
页数:8
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