A counterexample in copositive approximation |
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| Authors: | S P Zhou |
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| Institution: | (1) Department of Mathematics, Statistics and Computing Science, Dalhousie University, B3H 3J5 Halifax, Nova Scotia, Canada |
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| Abstract: | The present paper gives a converse result by showing that there exists a functionf ∈C
−1,1], which satisfies that sgn(x)f(x) ≥ 0 forx ∈ −1, 1], such that {fx75-1} whereE
n
(0)
(f, 1) is the best approximation of degreen tof by polynomials which are copositive with it, that is, polynomialsP withP(x(f(x) ≥ 0 for allx ∈ −1, 1],E
n(f) is the ordinary best polynomial approximation off of degreen. |
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| Keywords: | |
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