The study of condition numbers and perturbation analysis in least squares problems has become a cornerstone in numerical linear algebra, underpinning the reliability and accuracy of solutions to ...

We develop and analyze a first-order system least-squares spectral method for the second-order elliptic boundary value problem with variable coefficients. We first ...

This paper surveys perturbation theory for the pseudo-inverse (Moore-Penrose generalized inverse), for the orthogonal projection onto the column space of a matrix, and for the linear least squares ...