Abstract

We study the problem of sampling with derivatives in shift-invariant spaces generated by totally-positive functions of Gaussian type or by the hyperbolic secant. We provide sharp conditions in terms of weighted Beurling densities. As a by-product we derive new results about multi-window Gabor frames with respect to vectors of Hermite functions or totally positive functions.

Highlights

  • Introduction and ResultsIn the problem of sampling with derivatives, one tries to recover or approximate a function by sampling a number of its derivatives

  • We study the problem of sampling with multiplicities in the shift-invariant space

  • See [3] for one of the first nonuniform sampling theorems in shift-invariant spaces, [21] for nonuniform sampling with derivatives for bandlimited functions, and [2,5,23] for more recent examples of sufficient conditions for Hermite sampling in terms of the covering density

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Summary

Introduction and Results

In the problem of sampling with derivatives, one tries to recover or approximate a function by sampling a number of its derivatives. See [3] for one of the first nonuniform sampling theorems in shift-invariant spaces, [21] for nonuniform sampling with derivatives for bandlimited functions, and [2,5,23] for more recent examples of sufficient conditions for Hermite sampling in terms of the covering density. We relate the zero sets of functions in different shift-invariant spaces to each other. In this way we develop a direct line of arguments and avoid the detour in [15] via the characterization of Gaussian Gabor frames. As these are essentially known, we explain only the necessary modifications

Vector-Valued Shift-Invariant Spaces
Sampling and Weak Limits
Sets with Multiplicities and Derivatives
Sampling with Derivatives
Characterization of Sampling with Derivatives
Necessary Density Conditions
Density of Zero Sets in Shift-Invariant Spaces
The Gaussian
The Hyperbolic Secant
Transference of Zero Sets
Totally Positive Functions of Gaussian Type
Bandlimited Functions
Proof of the Sampling Theorems
Consequences for Gabor Frames
Multi-window Gabor Frames
Connection Between Sampling and Gabor Frames
Characterization of Multi-window Gabor Frames with Totally Positive Windows
Postponed Proofs
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