49 citations · 289 across the 45 of their papers we have counts for
4 papers · 2 filters
Generalised Weyl theorems and spectral pollution in the Galerkin method
Lyonell Boulton, Nabile Boussaid, Mathieu Lewin
We consider a general framework for investigating spectral pollution in the Galerkin method. We show how this phenomenon is characterised via the existence of particular Weyl seque…
Approximation properties of the -sine bases
Lyonell Boulton, Gabriel Lord
For the eigenfunctions of the non-linear eigenvalue problem associated to the one-dimensional -Laplacian are known to form a Riesz basis of . We examine in t…
On the convergence of second order spectra and multiplicity
Lyonell Boulton, Michael Strauss
Let A be a self-adjoint operator acting on a Hilbert space. The notion of second order spectrum of A relative to a given finite-dimensional subspace L has been studied recently in…
On a class of non-self-adjoint periodic boundary value problems with discrete real spectrum
Lyonell Boulton, Michael Levitin, Marco Marletta
In [arXiv:0801.0172] we examined a family of periodic Sturm-Liouville problems with boundary and interior singularities which are highly non-self-adjoint but have only real eigenva…