8 In his paper " Lagrange interpolation on Chebyshev points of two variables " (J. 9 220–238), Y. Xu proposed a set of Chebyshev like points for polynomial interpolation in the square 10 [−1, 1] 2 , and derived a compact form of the corresponding Lagrange interpolation formula. We inves-11 tigate computational aspects of the Xu polynomial interpolation formula like numerical stability and 12 ef...

We define a class of multivariate Laurent polynomials closely related to Chebyshev polynomials and prove the simple but somewhat surprising (in view of the fact that the signs of the coefficients of the Chebyshev polynomials themselves alternate) result that their coefficients are non-negative. As a corollary we find that Tn(c cos θ) and Un(c cos θ) are positive definite functions. We further s...

By using complex variable methods (steepest descent and residues) to asymptotically evaluate the coefftcient integrals, the numerical analysis of Hermite function series is discussed. There are striking similarities and differences with the author’s earlier work on Chebyshev polynomial methods (J. Comp. Phys. 45 (1982), 45-49) for infinite or semi-infinite domains. Like Chebyshev series, the He...

This paper establishes a direct method for solving variational problems via a set of Radial basis functions (RBFs) with Gauss-Chebyshev collocation centers. The method consist of reducing a variational problem into a mathematical programming problem. The authors use some optimization techniques to solve the reduced problem. Accuracy and stability of the multiquadric, Gaussian and inverse multiq...

‎By observing the equivalence of assertions on determining the jump of a‎ ‎function by its differentiated or integrated Fourier series‎, ‎we generalize a‎ ‎previous result of Kvernadze‎, ‎Hagstrom and Shapiro to the whole class of‎ ‎functions of harmonic bounded variation‎. ‎This is achieved without the finiteness assumption on‎ ‎the number of discontinuities‎. ‎Two results on determination of ...

We discuss two nonsmooth functions on Rn introduced by Nesterov. We show that the first variant is partly smooth in the sense of Lewis and that its only stationary point is the global minimizer. In contrast, we show that the second variant has 2n−1 Clarke stationary points, none of them local minimizers except the global minimizer, but also that its only Mordukhovich stationary point is the glo...

Cardinal polysplines of order p on annuli are functions in C2p−2 (Rn \ {0}) which are piecewise polyharmonic of order p such that ∆p−1S may have discontinuities on spheres in Rn, centered at the origin and having radii of the form ej , j ∈ Z. The main result is an interpolation theorem for cardinal polysplines where the data are given by sufficiently smooth functions on the spheres of radius ej...

ll rights reserved. Recently the Chebyshev kernel has been proposed for SVM and it has been proven that it is a valid kernel for scalar valued inputs in [11]. However in pattern recognition, many applications require multidimensional vector inputs. Therefore there is a need to extend the previous work onto vector inputs. In [11], although it is not stated explicitly, the authors recommend evalu...

The computation of spectral expansion coefficients is an important aspect in the implementation of spectral methods. In this paper, we explore two strategies for computing the coefficients of polynomial expansions of analytic functions, including Chebyshev, Legendre, ultraspherical and Jacobi coefficients, in the complex plane. The first strategy maximizes computational efficiency and results i...

When a function is singular at the ends of its expansion interval, its Chebyshev coefficients a, converge very poorly. We analyze three numerical strategies for coping with such singularities of the form (1 + x)~ log(1 f x), and in the process make some modest additions to the theory of Chebyshev expansions. The first two numerical methods are the convergence-improving changes of coordinate x =...