Constrained Approximation with Jacobi Weights
نویسندگان
چکیده
In this paper, we prove that for l = 1 or 2 the rate of best l-monotone polynomial approximation in the Lp norm (1 ≤ p ≤ ∞) weighted by the Jacobi weight wα ,β(x) ∶= (1 + x)α(1 − x)β with α, β > −1/p if p <∞, or α, β ≥ 0 if p =∞, is bounded by an appropriate (l + 1)-st modulus of smoothness with the same weight, and that this rate cannot be bounded by the (l+2)-ndmodulus. Related results on constrained weighted spline approximation and applications of our estimates are also given.
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