A Note on Weighted Polynomial Approximation with Varying Weights
β Scribed by A.B.J. Kuijlaars
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 199 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0021-9045
No coin nor oath required. For personal study only.
β¦ Synopsis
It is shown that if weighted polynomials w n P n with deg P n n converge uniformly on the support of the extremal measure associated with w, then they converge to 0 everywhere else. It is also shown that uniform approximation on the support can always be characterized by a closed subset Z having the property that a function can be approximated if and only if it vanishes on Z.
π SIMILAR VOLUMES
We consider two problems concerning uniform approximation by weighted rational functions [w n r n ] n=1 , where r n = p n Γq n has real coefficients, deg p n [:n] and deg q n [;n], for given :>0 and ; 0. For w(x) :=e x we show that on any interval [0, a] with a # (0, a^(:, ;)), every real-valued fun
The class of functions that can be uniformly approximated by weighted polynomials of the form w n P with deg P F n, depends on the behavior of the extremal n n measure associated with w as introduced by Mhaskar and Saff. It is shown that if in a neighborhood of a point t the extremal measure has a d