81 citations · 338 across the 34 of their papers we have counts for
10 papers · 1 filter
On the existence of optimizers for time-frequency concentration problems
Fabio Nicola, José Luis Romero, S. Ivan Trapasso
We consider the problem of the maximum concentration in a fixed measurable subset of the time-frequency space for functions . Th…
Sign retrieval in shift-invariant spaces with totally positive generator
José Luis Romero
We show that a real-valued function in the shift-invariant space generated by a totally positive function of Gaussian type is uniquely determined, up to a sign, by its absolute…
Sampling the flow of a bandlimited function
Akram Aldroubi, Karlheinz Gröchenig, Longxiu Huang +3
We analyze the problem of reconstruction of a bandlimited function from the space-time samples of its states resulting from the convolution with a kernel .…
The Nyquist sampling rate for spiraling curves
Philippe Jaming, Felipe Negreira, José Luis Romero
We consider the problem of reconstructing a compactly supported function from samples of its Fourier transform taken along a spiral. We determine the Nyquist sampling rate in terms…
Strict density inequalities for sampling and interpolation in weighted spaces of holomorphic functions
Karlheinz Gröchenig, Antti Haimi, Joaquim Ortega-Cerdà +1
Answering a question of Lindholm, we prove strict density inequalities for sampling and interpolation in Fock spaces of entire functions in several complex variables defined by a p…
Sharp results on sampling with derivatives in shift-invariant spaces and multi-window Gabor frames
Karlheinz Gröchenig, José Luis Romero, Joachim Stöckler
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 c…
Sharp rates of convergence for accumulated spectrograms
Luís Daniel Abreu, João Pereira, José Luis Romero
We investigate an inverse problem in time-frequency localization: the approximation of the symbol of a time-frequency localization operator from partial spectral information by the…
On accumulated spectrograms
Luís Daniel Abreu, Karlheinz Gröchenig, José Luis Romero
We study the eigenvalues and eigenfunctions of the time-frequency localization operator on a domain of the time-frequency plane. The eigenfunctions are the appropriate pr…
Exact and approximate expansions with pure Gaussian wavepackets
Maarten V. de Hoop, Karlheinz Gröchenig, José Luis Romero
We construct frames of wavepackets produced by parabolic dilation, rotation and translation of (a finite sum of) Gaussians and give asymptotics on the analogue of Daubechies frame…
Surgery of spline-type and molecular frames
José Luis Romero
We prove a result about producing new frames for general spline-type spaces by piecing together portions of known frames. Using spline-type spaces as models for the range of certai…