Seminário Análise Funcional e Aplicações 

01/06/2012, 15:00 — 16:00 — Sala P3.10, Pavilhão de Matemática
Helena Mascarenhas, Instituto Superior Técnico, UTL and CEAF

Spectral properties of variable coefficient Toeplitz matrices

Variable Toeplitz matrices, a generalization of the finite sections of a Toeplitz operator, have received increasing interest in recent years. They also appear under different names: generalized locally Toeplitz matrices, generalized convolutions or twisted Toeplitz matrices, with applications to discretized PDE, probability theory and statiscal mechanics. We will focus on sequences of variable- coefficient Toeplitz matrices with symbol on a class of the Wiener type. Using C*- algebras techniques, we will discuss the asymptotic behaviour of singular values, condition numbers and pseudospectrum, as well as the analogon of Fredolhm theory for sequences.