On square positive extensions and cubature formulas

  • Authors:
  • H. Michael Möller

  • Affiliations:
  • FB Mathematik der Universität, Dortmund, Germany

  • Venue:
  • Journal of Computational and Applied Mathematics - Special issue: Special functions in harmonic analysis and applications
  • Year:
  • 2007

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Abstract

We consider linear functionals Ld defined over Pd ⊂ P := R-|x1,...,xn| and study how to extend Ld to a square positive L : P → R, i.e. to a linear functional L with L(p2) ≥0 for all p ∈ P. We use the connection of square positive functionals to real ideals, to orthogonal polynomials, and to moment matrices. Finally, we report how such extension techniques are used to construct and analyse cubature formulas.