A function f with compactly supported Fourier transform can be approxi
mated by a step function a which coincides with f at regularly spaced
points sk, k epsilon Z. For suitable s, the functions f and a have the
same L(2) norm. By modifying a so that its Fourier transform shares t
he same compact support as that of f, an analytic function is obtained
which approximates f, the accuracy depending on s. e 1994 Academic Pr
ess, Inc.