Abstract.
A second look at the authors' [BDR1], [BDR2] characterization of the approximation order of a Finitely generated Shift-Invariant (FSI) subspace \(S(\Phi)\) of L 2(R d) results in a more explicit formulation entirely in terms of the (Fourier transform of the) generators \(\varphi\in\Phi\) of the subspace. Further, when the generators satisfy a certain technical condition, then, under the mild assumption that the set of 1-periodizations of the generators is linearly independent, such a space is shown to provide approximation order k if and only if \(\mathop{\rm span}\nolimits\{\varphi(\cdot-j): |j| < k, \varphi\in\Phi\}\) contains a \(\psi\) (necessarily unique) satisfying \(D^j\widehat{\psi}(\alpha)=\delta_j\delta_\alpha\) for |j|<k , \(\alpha\in 2\pi{\Bbb Z}^d\) . The technical condition is satisfied, e.g., when the generators are \(O(|\cdot|^{-\rho})\) at infinity for some \(\rho\) >k+d. In the case of compactly supported generators, this recovers an earlier result of Jia [J1], [J2].
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
March 19, 1996. Dates revised: September 6, 1996, March 4, 1997.
Rights and permissions
About this article
Cite this article
de Boor, C., DeVore, R. & Ron, A. Approximation Orders of FSI Spaces in L 2 (R d ) . Constr. Approx. 14, 631–652 (1998). https://doi.org/10.1007/s003659900094
Published:
Issue Date:
DOI: https://doi.org/10.1007/s003659900094