Eigenpairs of Wilkinson Matrices

Abstract

In the 1950s J. H. Wilkinson introduced two families of symmetric tridiagonal integer matrices. Most of the eigenvalues are close to diagonal entries. We develop the structure of their eigenvectors in a natural way which reveals that these eigenvectors all look the same to the naked eye. The shape of the envelopes is like twin peaks (or a badly dented bell curve). We also analyze the eigenvectors of the remaining noninteger eigenvalues.