Copositive approximation by rational functions with prescribed numerator degree

被引：0
作者：
YU Dansheng ZHOU Songping Department of MathematicsHangzhou Normal UniversityHangzhou China [1 ,21 ,310036 ]
Department of MathematicsStatistic and Computer ScienceStFrancis Xaiver UniversityAntigonishNova ScotiaCanada BG W Institute of MathematicsZhejiang SciTech UniversityHangzhou China [2 ,2 ,5 ,2 ,310028 ]
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来源：
Applied Mathematics:A Journal of Chinese Universities(Series B) | 2009年 / 24卷 / 04期
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中图分类号：
O174.41 [逼近论];
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摘要：
The paper proves that,if f(x)∈Lp[-1,1 ≤ p < ∞,changes sign l times in(-1,1),-1,1] then there exists a real rational function r(x) ∈ Rn(2μ-1)l which is copositive with f(x),such that the following Jackson type estimate ‖f-r‖p≤Cδl2μω holds,where μ is a natural nuωmber ≥(3/2)+(1/p),and Cδ is a positive constant depending only on δ.
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页码：411 / 416
页数：6
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