Abstract
We consider the problem of finding a best uniform approximation to the standard monomial on the unit ball in ℂ2 by polynomials of lower degree with complex coefficients. We reduce the problem to a one-dimensional weighted minimization problem on an interval. In a sense, the corresponding extremal polynomials are uniform counterparts of the classical orthogonal Jacobi polynomials. They can be represented by means of special conformal mappings on the so-called comb-like domains. In these terms, the value of the minimal deviation and the representation for a polynomial of best approximation for the original problem are given. Furthermore, we derive asymptotics for the minimal deviation.
Original language | English |
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Pages (from-to) | 13-24 |
Number of pages | 12 |
Journal | Computational Methods and Function Theory |
Volume | 11 |
Issue number | 1 |
DOIs | |
State | Published - 2011 |
Externally published | Yes |
Keywords
- Asymptotics
- Conformal mapping
- Minimal deviation
- Polynomial approximation
- Several variables
- Uniform norm