Unisolvence of Symmetric Node Patterns for Polynomial Spaces on the Simplex

Journal Article (2023)
Author(s)

WA Mulder (TU Delft - Applied Geophysics and Petrophysics, Shell Global Solutions International B.V.)

Research Group
Applied Geophysics and Petrophysics
Copyright
© 2023 W.A. Mulder
DOI related publication
https://doi.org/10.1007/s10915-023-02161-1
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 W.A. Mulder
Research Group
Applied Geophysics and Petrophysics
Issue number
2
Volume number
95
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Abstract

Finite elements with polynomial basis functions on the simplex with a symmetric distribution of nodes should have a unique polynomial representation. Unisolvence not only requires that the number of nodes equals the number of independent polynomials spanning a polynomial space of a given degree, but also that the Vandermonde matrix controlling their mapping to the Lagrange interpolating polynomials can be inverted. Here, a necessary condition for unisolvence is presented for polynomial spaces that have non-decreasing degrees when going from the edges and the various faces to the interior of the simplex. It leads to a proof of a conjecture on a necessary condition for unisolvence, requiring the node pattern to be the same as that of the regular simplex.