“…There exists by now a considerable body of literature concerned with the application of Ulam-type methods to approximate the leading eigenvalue and eigenfunction as well as subleading eigenvalues of transfer operators, including those arising from higher-dimensional expanding or hyperbolic maps, see [F1,BlK,DJ,BlKL,F2,BahB,GN,CrF1] to name but a few. For dynamical system with higher regularity, the speed of convergence of projection-based methods can be improved by choosing projections onto subspaces spanned by functions of higher smoothness, see [Liv] for a discussion of a general strategy or [BalH] for an approach using wavelets.…”