# Optimal order integration on the sphere

Hesse, Kerstin and Sloan, Ian H (2006) Optimal order integration on the sphere. In: Li, T and Zhang, P (eds.) Frontiers and Prospects on Contemporary Applied Mathematics. Higher Education Press and World Scientific, pp. 59-70. ISBN 978-7-040-18575-1

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## Abstract

This paper reviews some recent developments in cubature over the sphere $S^2$ for functions in Sobolev spaces. More precisely, for an $m$-point cubature rule $Q_m$ we consider the worst-case (cubature) error, denoted by $E(Q_m;H^s)$, of functions in the unit ball of the Sobolev space $H^s=H^s(S^2)$, with $s&gt;1$. The following recent results are reviewed in this paper: For any sequence $(Q_{m(n)})_{n\\in\\mathbb{N}}$ of positive weight $m(n)$-point cubature rules $Q_{m(n)}$, where $Q_{m(n)}$ integrates all spherical polynomials of degree $\\leq n$ exactly, the worst-case error in $H^s$ satisfies the estimate $E(Q_{m(n)};H^s)\\leq c_s n^{-s}$ with a universal constant $c_s&gt;0$. Whenever $m(n)=O(n^2)$ we deduce $E(Q_{m(n)};H^s)\\leq c_s m(n)^{-s/2}$, where the constant $c_s$ now depends on the constant in $m(n)=O(n^2)$. This rate of convergence is optimal since it has also been shown that there exists a universal constant $\\tilde{c}_s&gt;0$ such that for any $m$-point cubature rule $Q_m$, the worst-case error in $H^s$ with $s&gt;1$ satisfies $E(Q_m;H^s)\\geq\\tilde{c}_s m^{-s/2}$. For example, sequences $(Q_{m(n)})$ of positive weight product rules with $m(n)=O(n^2)$ achieve the optimal order of convergence $O(m(n)^{-s/2})$. So too, if the weights are all positive, do sequences $(Q_{m(n)})$ of interpolatory cubature rules based on extremal fundamental systems.

Item Type: Book Section School of Mathematical and Physical Sciences > Mathematics Kerstin Hesse 06 Feb 2012 20:45 11 Apr 2012 11:30 http://sro.sussex.ac.uk/id/eprint/27985