“…While the Legendre-and Chebyshev-spectral approximations for PDEs in bounded domains have achieved great success and popularity in recent years (see, e.g., [3,11,16,19]), spectral approximations for PDEs in unbounded domains have received only limited attention. Some earlier works on the convergence analysis of spectral methods in unbounded domains have been given by Funaro and Kavian [17], Guo [23] (on Hermite spectral approximations); by Mavriplis [32], Shen [37] (on Laguerre approximations); by Boyd [6], Grosch and Orszag [20] (on rational polynomial approximations).…”