Journal of Computational Physics
Construction of Lanczos type filters for the Fourier series approximation
Applied Numerical Mathematics
Journal of Computational Physics
Journal of Computational and Applied Mathematics
Optimal Gegenbauer quadrature over arbitrary integration nodes
Journal of Computational and Applied Mathematics
Gibbs phenomenon removal by adding Heaviside functions
Advances in Computational Mathematics
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The Fourier--Gegenbauer (FG) method, introduced by [Gottlieb, Shu, Solomonoff, and Vandeven, ICASE Report 92-4, Hampton, VA, 1992] is aimed at removing the Gibbs phenomenon; that is, recovering the point values of a nonperiodic function from its Fourier coefficients. In this paper, we discuss some numerical aspects of the FG method related to its {\em pseudospectral\/} implementation. In particular, we analyze the behavior of the Gegenbauer series with a moderate (several hundred) number of terms suitable for computations. We also demonstrate the ability of the FG method to get a spectrally accurate approximation on small subintervals for rapidly oscillating functions or functions having steep profiles.Bearing on the previous analysis, we suggest a high-order spectral Fourier method for the solution of nonperiodic differential equations. It includes a polynomial subtraction technique to accelerate the convergence of the Fourier series and the FG algorithm to evaluate derivatives on the boundaries of nonperiodic functions. The present hybrid Fourier--Gegenbauer (HFG) method possesses better resolution properties than the original FG method. The precision of this method is demonstrated by solving stiff elliptic problems with steep solutions.