English

On the paths of steepest descent for the norm of a one variable complex polynomial

Complex Variables 2022-02-02 v2

Abstract

We consider paths of steepest descent, in the complex plane, for the norm of a non-constant one variable polynomial ff. We show that such paths, starting from a zero of the logarithmic derivative of ff and ending in a root of ff, draw a tree in the complex plane, and we give an upper bound estimate on their lengths. In some cases, we obtain a finer estimate that depends only on the set of roots of ff, not on their multiplicity, and we wonder if this can be done in general. We also extend this question to finite Blaschke products for the unit disk.

Keywords

Cite

@article{arxiv.2010.01583,
  title  = {On the paths of steepest descent for the norm of a one variable complex polynomial},
  author = {Damien Roy},
  journal= {arXiv preprint arXiv:2010.01583},
  year   = {2022}
}

Comments

Several typos corrected, addition of a section on Blaschke products, 7 pages, 2 figures