A Method of Order 1+SQRT(3) for Computing the Smallest Eigenvalue of a Symmetric Toeplitz Matrix

Abstract

In this note we discuss a method of order 1+sqrt(3) for computing the smallest eigenvalue lambda_1 of a symmetric and positive definite Toeplitz matrix. It generalizes and improves a method introduced in cite{MacVos97} which is based on rational Hermitean interpolation of the secular equation. Taking advantage of a further rational approximation of the secular equation which is essentially for free and which yields lower bounds of lambda_1 we obtain an improved stopping criterion.