Matrix calculations underlie countless problems in science, mathematics, and engineering. When the involved matrices are highly structured, displacement operators can be used to accelerate fundamental operations such as matrix-vector multiplication. In this thesis, we provide an introduction to the theory of displacement operators and study the interplay between displacement and natural matrix ...

We generalize to several variables Kurbanov and Maksimov’s result that all linear polynomial operators can be expressed as a formal sum ∑∞ k=0 ak(X) D k in terms of the derivative D (or any degree reducing operator) and multiplication by x. In contrast, we characterize those linear operators that can be expressed as ∑∞ k=0 fk(D) X k and give several examples. Generalizations to several variable...

Commutators of a large class of bilinear operators and multiplication by functions in a certain subspace of the space of functions of bounded mean oscillations are shown to be jointly compact. Under a similar commutation, fractional integral versions of the bilinear Hilbert transform yield separately compact operators.

We estimate the essential norm of a weighted composition operator relatively to the class of Dunford-Pettis operators or the class of weakly compact operators, on the space H∞ of Dirichlet series. As particular cases, we obtain the precise value of the generalized essential norm of a composition operator and of a multiplication operator.

We introduce a class of Gabor-type matrices and show that the product of two Gabor-type matrices is still a Gabor-type matrix possessing the same type. The key point is based on the fact that the multiplication of Gabor-type matrices can be converted into the \multiplication" of small block matrices. We propose an eecient algorithm, the specially devised block-multiplication. As an interesting ...