The limits of refinable functions

Authors:
Gilbert Strang and Ding-Xuan Zhou

Journal:
Trans. Amer. Math. Soc. **353** (2001), 1971-1984

MSC (2000):
Primary 42C40, 41A25; Secondary 65F15

Published electronically:
January 4, 2001

MathSciNet review:
1813602

Full-text PDF Free Access

Abstract | References | Similar Articles | Additional Information

A function is refinable ( ) if it is in the closed span of . This set is not closed in , and we characterize its closure. A necessary and sufficient condition for a function to be refinable is presented without any information on the refinement mask. The Fourier transform of every vanishes on a set of positive measure. As an example, we show that all functions with Fourier transform supported in are the limits of refinable functions. The relation between a refinable function and its mask is studied, and nonuniqueness is proved. For inhomogeneous refinement equations we determine when a solution is refinable. This result is used to investigate refinable components of multiple refinable functions. Finally, we investigate fully refinable functions for which all translates (by any real number) are refinable.

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Additional Information

**Gilbert Strang**

Affiliation:
Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

Email:
gs@math.mit.edu

**Ding-Xuan Zhou**

Affiliation:
Department of Mathematics, City University of Hong Kong, Tat Chee Avenue, Kow- loon, Hong Kong, P. R. China

Email:
mazhou@math.cityu.edu.hk

DOI:
http://dx.doi.org/10.1090/S0002-9947-01-02668-X

Keywords:
Refinable function,
Fourier transform,
band-limited function,
refinement mask,
inhomogeneous refinement equation,
multiple refinable function,
fully refinable function

Received by editor(s):
May 15, 1998

Received by editor(s) in revised form:
November 3, 1999

Published electronically:
January 4, 2001

Additional Notes:
Research supported in part by Research Grants Council of Hong Kong.

Article copyright:
© Copyright 2001
American Mathematical Society