Journal of Computational and Applied Mathematics
On the coefficients of integrated expansions of Bessel polynomials
Journal of Computational and Applied Mathematics
Efficient spectral-Galerkin methods for polar and cylindrical geometries
Applied Numerical Mathematics
Mathematics and Computers in Simulation
On the coefficients of integrated expansions of Bessel polynomials
Journal of Computational and Applied Mathematics
Matrix decomposition algorithms for elliptic boundary value problems: a survey
Numerical Algorithms
A spectral method for elliptic equations: the Neumann problem
Advances in Computational Mathematics
Journal of Computational Physics
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It is well known that spectral methods (tau, Galerkin, collocation) have a condition number of O(N4) (N is the number of retained modes of polynomial approximations). This paper presents some efficient spectral algorithms, which have a condition number of O(N2), based on the ultraspherical-Galerkin methods for second-order elliptic equations in one and two space variables. The key to the efficiency of these algorithms is to construct appropriate base functions, which lead to systems with specially structured matrices that can be efficiently inverted. The complexities of the algorithms are a small multiple of Nd+1 operations for a d-dimensional domain with (N-1)d unknowns, while the convergence rates of the algorithms are exponential for problems with smooth solutions.