Journal of Shanghai Jiaotong University

• Automation Technique, Computer Technology •     Next Articles

An Improved Algorithm for Real Root Isolation of Univariate Polynomials

LIU Dong1,FENG Yong1,ZHANG Caihuan2,ZHAO Xianghui1   

  1. (1.Chengdu Institute of Computer Applications, Chinese Academy of Sciences, Chengdu 610041, China;
    2.Department of Mathematics, Luoyang Normal University, Luoyang 471022, Henan,China)
  • Received:2010-01-18 Revised:1900-01-01 Online:2010-11-30 Published:2010-11-30

Abstract: An improved algorithm for real root isolation of univariate polynomials was proposed mainly based on bisection method and a kind of specially designed efficient interval Newton operator. Its structure is similar to Trealroot, a function in Maple package Discoverer, however, it is more efficient than Trealroot for sparse polynomials with large degrees and few terms. Generally speaking, performing Taylor shift is very costly, so Trealroot uses many techniques to decrease the number of Taylor shifts. Different from Trealroot, the proposed algorithm performs a specially designed efficient exact interval Newton operator to rule out intervals not containing real zeros quickly and avoids completely Taylor shifts. The algorithm is super efficient for sparse polynomials. The polynomial is sparser, and the algorithm is more efficient. A large number of polynomials generated randomly by Maple were tested, compared with Trealroot and realroot (a function in Maple), and the result was reported.

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