Abstract
We first recall some properties of infinite tridiagonal
matrices considered as matrix transformations in sequence spaces of the forms
sξ, sξ∘, sξ(c), or lp(ξ). Then, we give some results on the finite section
method for approximating a solution of an infinite linear system. Finally,
using a quasi-Newton method, we construct a sequence that converges fast to a
solution of an infinite linear system.