Accurate simple zeros of polynomials in floating point arithmetic

  • Authors:
  • Stef Graillat

  • Affiliations:
  • UPMC Univ Paris 06, CNRS, UMR 7606, LIP6, 4 place Jussieu, F-75252, Paris cedex 05, France

  • Venue:
  • Computers & Mathematics with Applications
  • Year:
  • 2008

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Abstract

In the paper, we examine the local behavior of Newton's method in floating point arithmetic for the computation of a simple zero of a polynomial assuming that an good initial approximation is available. We allow an extended precision (twice the working precision) in the computation of the residual. We prove that, for a sufficient number of iterations, the zero is as accurate as if computed in twice the working precision. We provide numerical experiments confirming this.