On the Geometry of Graeffe Iteration

Fuente: arXiv
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Autori principali: Malajovich, Gregorio, Zubelli, Jorge P.
Natura: Preprint
Pubblicazione: 1999
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author Malajovich, Gregorio
Zubelli, Jorge P.
author_facet Malajovich, Gregorio
Zubelli, Jorge P.
contents A new version of the Graeffe algorithm for finding all the roots of univariate complex polynomials is proposed. It is obtained from the classical algorithm by a process analogous to renormalization of dynamical systems. This iteration is called Renormalized Graeffe Iteration. It is globally convergent, with probability 1. All quantities involved in the computation are bounded, once the initial polynomial is given (with probability 1). This implies remarkable stability properties for the new algorithm, thus overcoming known limitations of the classical Graeffe algorithm. If we start with a degree-$d$ polynomial, each renormalized Graeffe iteration costs $O(d^2)$ arithmetic operations, with memory $O(d)$. A probabilistic global complexity bound is given. The case of univariate real polynomials is briefly discussed. A numerical implementation of the algorithm presented herein allowed us to solve random polynomials of degree up to 1000.
format Preprint
id arxiv_https___arxiv_org_abs_math_9908149
institution arXiv
publishDate 1999
record_format arxiv
spellingShingle On the Geometry of Graeffe Iteration
Malajovich, Gregorio
Zubelli, Jorge P.
Numerical Analysis
A new version of the Graeffe algorithm for finding all the roots of univariate complex polynomials is proposed. It is obtained from the classical algorithm by a process analogous to renormalization of dynamical systems. This iteration is called Renormalized Graeffe Iteration. It is globally convergent, with probability 1. All quantities involved in the computation are bounded, once the initial polynomial is given (with probability 1). This implies remarkable stability properties for the new algorithm, thus overcoming known limitations of the classical Graeffe algorithm. If we start with a degree-$d$ polynomial, each renormalized Graeffe iteration costs $O(d^2)$ arithmetic operations, with memory $O(d)$. A probabilistic global complexity bound is given. The case of univariate real polynomials is briefly discussed. A numerical implementation of the algorithm presented herein allowed us to solve random polynomials of degree up to 1000.
title On the Geometry of Graeffe Iteration
topic Numerical Analysis
url https://arxiv.org/abs/math/9908149