Search Results for author: Cristian Rusu

Found 15 papers, 6 papers with code

On learning with shift-invariant structures

1 code implementation3 Dec 2018 Cristian Rusu

We describe new results and algorithms for two different, but related, problems which deal with circulant matrices: learning shift-invariant components from training data and calculating the shift (or alignment) between two given signals.

Dictionary Learning Retrieval

Approximate Eigenvalue Decompositions of Linear Transformations with a Few Householder Reflectors

1 code implementation19 Nov 2018 Cristian Rusu

The ability to decompose a signal in an orthonormal basis (a set of orthogonal components, each normalized to have unit length) using a fast numerical procedure rests at the heart of many signal processing methods and applications.

Learning Multiplication-free Linear Transformations

1 code implementation9 Dec 2018 Cristian Rusu

In this paper, we propose several dictionary learning algorithms for sparse representations that also impose specific structures on the learned dictionaries such that they are numerically efficient to use: reduced number of addition/multiplications and even avoiding multiplications altogether.

Dictionary Learning

Efficient and Parallel Separable Dictionary Learning

1 code implementation7 Jul 2020 Cristian Rusu, Paul Irofti

Separable, or Kronecker product, dictionaries provide natural decompositions for 2D signals, such as images.

Dictionary Learning Image Denoising

Dictionary Learning with Uniform Sparse Representations for Anomaly Detection

1 code implementation11 Jan 2022 Paul Irofti, Cristian Rusu, Andrei Pătraşcu

In this paper we use a particular DL formulation that seeks uniform sparse representations model to detect the underlying subspace of the majority of samples in a dataset, using a K-SVD-type algorithm.

Anomaly Detection Dictionary Learning

Learning Fast Sparsifying Transforms

no code implementations24 Nov 2016 Cristian Rusu, John Thompson

We also propose a method to construct fast square but non-orthogonal dictionaries that are factorized as a product of few transforms that can be viewed as a further generalization of Givens rotations to the non-orthogonal setting.

Dictionary Learning

Fast Orthonormal Sparsifying Transforms Based on Householder Reflectors

no code implementations24 Nov 2016 Cristian Rusu, Nuria Gonzalez-Prelcic, Robert Heath

Dictionary learning is the task of determining a data-dependent transform that yields a sparse representation of some observed data.

Dictionary Learning

Fast approximation of orthogonal matrices and application to PCA

no code implementations18 Jul 2019 Cristian Rusu, Lorenzo Rosasco

We study the problem of approximating orthogonal matrices so that their application is numerically fast and yet accurate.

Constructing fast approximate eigenspaces with application to the fast graph Fourier transforms

no code implementations22 Feb 2020 Cristian Rusu, Lorenzo Rosasco

We investigate numerically efficient approximations of eigenspaces associated to symmetric and general matrices.

A Note on Shift Retrieval Problems

no code implementations28 Jun 2019 Cristian Rusu

In this note, we discuss the shift retrieval problems, both classical and compressed, and provide connections between them using circulant matrices.

Retrieval

An iterative coordinate descent algorithm to compute sparse low-rank approximations

no code implementations30 Jul 2021 Cristian Rusu

In this paper, we describe a new algorithm to build a few sparse principal components from a given data matrix.

Dimensionality Reduction

Low complexity joint position and channel estimation at millimeter wave based on multidimensional orthogonal matching pursuit

no code implementations7 Apr 2022 Joan Palacios, Nuria González-Prelcic, Cristian Rusu

Compressive approaches provide a means of effective channel high resolution channel estimates in millimeter wave MIMO systems, despite the use of analog and hybrid architectures.

Position

Multidimensional orthogonal matching pursuit: theory and application to high accuracy joint localization and communication at mmWave

no code implementations24 Aug 2022 Joan Palacios, Nuria González-Prelcic, Cristian Rusu

Greedy approaches in general, and orthogonal matching pursuit in particular, are the most commonly used sparse recovery techniques in a wide range of applications.

Kernel t-distributed stochastic neighbor embedding

no code implementations13 Jul 2023 Denis C. Ilie-Ablachim, Bogdan Dumitrescu, Cristian Rusu

This paper presents a kernelized version of the t-SNE algorithm, capable of mapping high-dimensional data to a low-dimensional space while preserving the pairwise distances between the data points in a non-Euclidean metric.

Clustering

Learning Explicitly Conditioned Sparsifying Transforms

1 code implementation5 Mar 2024 Andrei Pătraşcu, Cristian Rusu, Paul Irofti

Sparsifying transforms became in the last decades widely known tools for finding structured sparse representations of signals in certain transform domains.

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