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Degree of approximation of functions of different classes has been studied by several researchers by different summability methods. In the proposed paper, we have established a new theorem for the approximation of a signal (function) belonging to the W(Lr, ξ(t))-class by (..., pn, qn)(E, s)-product summability means of a Fourier series. The result obtained here, generalizes several known theorems. [ABSTRACT FROM AUTHOR]

For given p ∈ [ 1 , ∞ ] and g ∈ L p ( R ) , we establish the existence and uniqueness of solutions f ∈ L p ( R ) , to the equation f ( x ) − a f ( b x ) = g ( x ) , where a ∈ R , b ∈ R ∖ { 0 } , and | a | ≠ | b | 1 / p . Solutions include well-known nowhere differentiable functions such as those of Bolzano, Weierstrass, Hardy, and many others. Connections and consequences in the theory of fractal interpolation, approximation theory, and Fourier analysis are established. [ABSTRACT FROM AUTHOR]

In the present study, a new theorem on the degree of approximation of function f, conjugate to a periodic function f belonging to weighted W(Lr, ξ(t))-class using semimonotonicity on the generating sequence {pn} has been established. [ABSTRACT FROM AUTHOR]

A new estimate for the degree of approximation of a function ... ∊ Hω class by (Np · E¹) means of its Fourier series has been determined. Here, we extend the results of Singh and Mahajan (2008) which in turn generalize the result of Lal and Yadav (2001). Some corollaries have also been deduced from our main theorem. [ABSTRACT FROM AUTHOR]

Abstract: In this paper modified variants of the sparse Fourier transform algorithms from Iwen (2010) [32] are presented which improve on the approximation error bounds of the original algorithms. In addition, simple methods for extending the improved sparse Fourier transforms to higher dimensional settings are developed. As a consequence, approximate Fourier transforms are obtained which will identify a near-optimal k-term Fourier series for any given input function, , in time (neglecting logarithmic factors). Faster randomized Fourier algorithm variants with runtime complexities that scale linearly in the sparsity parameter k are also presented. [Copyright &y& Elsevier]

Abstract: The Variational Theory of Complex Rays (VTCR) is a wave-based computational approach dedicated to the resolution of medium-frequency problems. It uses a variational formulation of the problem which enables one to use any type of shape function within the substructures provided that it satisfies the governing equation. Thus, the solution can be approximated using plane waves, which is very interesting in the medium-frequency vibration domain and also leads to a strong convergence of the method. In the previous works, this was shown in the case of acoustic problems in which the amplitudes of the plane waves were calculated as wavebands. In this paper, we propose a new approximation of these amplitudes based on Fourier series. We show that this approach increases the robustness of the method, makes it more efficient numerically and extends its applicability to somewhat higher frequencies. [Copyright &y& Elsevier]

We analyze the asymptotic behavior of the Apostol-Bernoulli polynomials Bn(χ; λ) in detail. The starting point is their Fourier series on [0, 1] which, it is shown, remains valid as an asymptotic expansion over compact subsets of the complex plane. This is used to determine explicit estimates on the constants in the approximation, and also to analyze oscillatory phenomena which arise in certain cases. These results are transferred to the Apostol-Euler polynomials En(χ; λ) via a simple relation linking them to the Apostol-Bernoulli polynomials. [ABSTRACT FROM AUTHOR]

In this paper, two quite new theorems on degree of approximation of conjugate of functions f ϵ Lipα class and f ϵ W (Lr, ξ(t)) class using (E,1) (C,1) product summability means of conjugate Fourier series have been established. [ABSTRACT FROM AUTHOR]

Abstract: In order to approximate functions defined on and having exponential singularities at the endpoints of the interval, we study the behavior of some modified Fourier Sums in an orthonormal system related to exponential weights. We give necessary and sufficient conditions for the boundedness of the related operators in suitable weighted -spaces, with . Then, in these spaces, these processes converge with the order of the best polynomial approximation. [Copyright &y& Elsevier]

Abstract: Hurwitz found the Fourier expansion of the Bernoulli polynomials over a century ago. In general, Fourier analysis can be fruitfully employed to obtain properties of the Bernoulli polynomials and related functions in a simple manner. In addition, applying the technique of Möbius inversion from analytic number theory to Fourier expansions, we derive identities involving Bernoulli polynomials, Bernoulli numbers, and the Möbius function; this includes formulas for the Bernoulli polynomials at rational arguments. Finally, we show some asymptotic properties concerning the Bernoulli and Euler polynomials. [ABSTRACT FROM AUTHOR]

Modified Fourier series have recently been introduced as an adjustment of classical Fourier series for the approximation of nonperiodic functions defined on $ d$ In this paper we extend Eckhoff's method to the convergence acceleration of multivariate modified Fourier series. By suitable augmentation of the approximation basis we demonstrate how to increase the convergence rate to an arbitrary algebraic order. Moreover, we illustrate how numerical stability of the method can be improved by utilising appropriate auxiliary functions. In the univariate setting it is known that Eckhoff's method exhibits an auto-correction phenomenon. We extend this result to the multivariate case. Finally, we demonstrate how a significant reduction in the number of approximation coefficients can be achieved by using a hyperbolic cross index set. [ABSTRACT FROM AUTHOR]

Fourier interpolation is a useful tool to reconstruct continuous signals from discrete samples. This correspondence derives Fourier interpolation expression from Fourier series for periodic signals and investigates its error expression and upper bound for general band-limited signals. Two numerical examples are given to interpret the meaning of the formulas. [ABSTRACT FROM AUTHOR]

In their paper, Good and Gaskins determine empirically the number of terms required in Hermite and Fourier expansions to obtain equivalent degrees of approximation. The argument that a sign pattern in the coefficients in the Hermite expansion of a function slows the convergence is ingenious, but there is another reason for the better approximation by Fourier series than for Hermite series that is probably more important.

The article presents information density estimation and Bump-Hunting by the penalized liklihood method. The argument that a sign pattern in the coefficients in the Hermite expansion of a function slows the convergence is ingenious, but there is another reason for the better approximation by Fourier series than for Hermite series that is probably more important.