| DEGREE OF COPOSITIVE POLYNOMIAL APPROXIMATION |
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| 作者姓名： | Yu Xiangming |
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| 作者单位： | Department of |
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| 摘 要： | Denoteby _n(f) the degree of copositive approximation to f(x) by polynomials of degree≤n. For function f(x) ∈ C~k-1, 1] which alternates in sign finitely many timesin -1, 1], the author obtains the following Jackson type estimates_n(f)≤Cn~(-k)w(f~(k), 1/n)foa any positive integer k.
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| 收稿时间： | 1987/6/23 0:00:00 |
DEGREE OF COPOSITIVE POLYNOMIAL APPROXIMATION |
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| Yu Xiangming.DEGREE OF COPOSITIVE POLYNOMIAL APPROXIMATION[J].Chinese Annals of Mathematics,Series B,1989,10(3):409-415. |
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| Authors: | Yu Xiangming |
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| Institution: | Department of Mathematics, Nanjing University, Nanjing, Jiangsu, China. |
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| Abstract: | Denote by $\{E_n}(f)\]$ the degree of copositive approximation to $\f(x)\]$ by polynomials of
degree $\ \le n\]$. For function $\f(x) \in {C^k} - 1,1]\]$ which alternates in sign finitely many timesin
$\ - 1,1]\]$, the author obtains the following Jackson type estimates.
$\{E_n}(f) \le C{n^{ - k}}\omega ({f^{(k)}},1/n)\]$
for any positive integer $k$. |
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| Keywords: | |
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