Remarks on Inner Functions and Optimal Approximants

关于切比雪夫有理函数、多点Padé逼近和噪声的一个注记

A remark on Chebyshev rational functions, multipoint Padé approximants and Noise

受多点Padé逼近在物理学界兴趣的启发，讨论切比雪夫有理函数如何产生多点Padé逼近，给出递推关系和连分数，并数值展示噪声对插值方案的影响。

Zeros of optimal polynomial approximants in $\ell^p_{A}$

The study of inner and cyclic functions in $\ell^p_A$ spaces requires a better understanding of the zeros of the so-called optimal polynomial approximants. We determine that a point of the complex plane is the zero of an optimal polynomial approximant for some element of $\ell^p_A$ if and only if it lies outside of a closed disk (centered at the origin) of a particular radius which depends on the value of $p$. We find the value of this radius for $p\neq 2$. In addition, for each positive integer $d$ there is a polynomial $f_d$ of degree at most $d$ that minimizes the modulus of the root of its…