Multivariate approximation by a combination of modified Taylor polynomials

  • Authors:

  • Allal Guessab;Otheman Nouisser;Gerhard Schmeisser

  • Affiliations:

  • Laboratoire de Mathématiques Appliquées de Pau, Université de Pau et des Pays de l'Adour, Pau, France;Laboratoire de Mathématiques Appliquées de Pau, Université de Pau et des Pays de l'Adour, Pau, France;Mathematical Institute, University of Erlangen-Nuremberg, Erlangen, Germany

  • Venue:
  • Journal of Computational and Applied Mathematics
  • Year:
  • 2006

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Abstract

We study an approximation of a multivariate function f by an operator of the form Σi=1N˜r|f, xi|(x)φi(x), where φ1,...,φN are certain basis functions and ˜r|f, xi|(x) are modified Taylor polynomials of degree r expanded at xi. The modification is such that the operator has highest degree of algebraic precision. In the univariate case, this operator was investigated by Xuli [Multinode higher order expansions of a function, J. Approx. Theory 124 (2003) 242-253]. Special attention is given to the case where the basis functions are a partition of unity of linear precision. For this setting, we establish two types of sharp error estimates. In the two-dimensional case, we show that this operator gives access to certain classical interpolation operators of the finite element method. In the case where φ1,...,φN are multvariate Bernstein polynomials, we establish an asymptotic representation for the error as N → ∞