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- Bogdan Dumitrescu, Riitta Niemistö
- IEEE Transactions on Signal Processing
- 2004

In this paper, we consider infinite impulse response (IIR) filter design where both magnitude and phase are optimized using a weighted and sampled least-squares criterion. We propose a new convex stability domain defined by positive realness for ensuring the stability of the filter and adapt the Steiglitz-McBride (SM), Gauss-Newton (GN), and classical… (More)

- B. Dumitrescu
- IEEE Transactions on Signal Processing
- 2006

We propose a characterization of multivariate trigonometric polynomials that are positive on a given frequency domain. The positive polynomials are parameterized as a linear function of sum-of-squares polynomials and so semidefinite programming (SDP) is applicable. The frequency domain is expressed via the positivity of some trigonometric polynomials. We… (More)

- Cristian Rusu, Bogdan Dumitrescu
- IEEE Signal Processing Letters
- 2012

The problem of training a dictionary for sparse representations from a given dataset is receiving a lot of attention mainly due to its applications in the fields of coding, classification and pattern recognition. One of the open questions is how to choose the number of atoms in the dictionary: if the dictionary is too small then the representation errors… (More)

- Cristian Rusu, Bogdan Dumitrescu
- Signal Processing
- 2012

Designing sparse 1D and 2D filters has been the object of research in recent years due mainly to the developments in the field of sparse representations. The main goal is to reduce the implementation complexity of a filter while keeping as much of the performance as possible. This paper describes a new method for designing sparse filters in the minimax… (More)

- Cristian Rusu, Bogdan Dumitrescu
- 21st European Signal Processing Conference…
- 2013

In the field of sparse representations, the overcomplete dictionary learning problem is of crucial importance and has a growing application pool where it is used. In this paper we present an iterative dictionary learning algorithm based on the singular value decomposition that efficiently construct unions of orthonormal bases. The important innovation… (More)

- Cristian Rusu, Bogdan Dumitrescu, Sotirios A. Tsaftaris
- IEEE Signal Processing Letters
- 2014

In this letter we give efficient solutions to the construction of structured dictionaries for sparse representations. We study circulant and Toeplitz structures and give fast algorithms based on least squares solutions. We take advantage of explicit circulant structures and we apply the resulting algorithms to shift-invariant learning scenarios. Synthetic… (More)

- Bogdan Dumitrescu, Ioan Tabus, Petre Stoica
- IEEE Trans. Signal Processing
- 2001

- Bogdan Dumitrescu, Alexandru Onose, Petri Helin, Ioan Tabus
- IEEE Transactions on Signal Processing
- 2012

Starting from the orthogonal (greedy) least squares method, we build an adaptive algorithm for finding online sparse solutions to linear systems. The algorithm belongs to the exponentially windowed recursive least squares (RLS) family and maintains a partial orthogonal factorization with pivoting of the system matrix. For complexity reasons, the… (More)

- Bogdan Dumitrescu, Jean-Louis Roch, Denis Trystram
- Parallel Algorithms Appl.
- 1994

Sequential fast matrix multiplication algorithms of Strassen and Winograd are studied ; the complexity bound given by Strassen is improved. These algorithms are parallelized on MIMD distributed memory architectures of ring and torus topologies; a generalization to a hyper-torus is also given. Complexity and efficiency are analyzed and good asymptotic… (More)

- Roh Tae, B. Dumitrescu, L. Vandenberghe
- IEEE Journal of Selected Topics in Signal…
- 2007

We discuss a method for multidimensional FIR filter design via sum-of-squares formulations of spectral mask constraints. The sum-of-squares optimization problem is expressed as a semidefinite program with low-rank structure, by sampling the constraints using discrete cosine and sine transforms. The resulting semidefinite program is then solved by a… (More)