Representation of reproducing kernels and the Lebesgue constants on the ball

Authors
Citation
Y. Xu, Representation of reproducing kernels and the Lebesgue constants on the ball, J APPROX TH, 112(2), 2001, pp. 295-310
Citations number
10
Categorie Soggetti
Mathematics
Journal title
JOURNAL OF APPROXIMATION THEORY
ISSN journal
00219045 → ACNP
Volume
112
Issue
2
Year of publication
2001
Pages
295 - 310
Database
ISI
SICI code
0021-9045(200110)112:2<295:RORKAT>2.0.ZU;2-U
Abstract
For the weight function (1 - parallel tox parallel to (2))(mu -1/2) on the unit ball, a closed formula of the reproducing kernel is modified to includ e the case -1/2 < mu < 0. The new formula is used to study the orthogonal p rojection of the weighted L-2 space onto the space of polynomials of degree at most n, and it is proved that the uniform norm of the projection operat or has the growth rate of for mu < 0, which is the smallest possible growth rate among all projections, while the rate for mu greater than or equal to 0 is n(mu+(d-1)/2). (C) 2001 Academic Press.