Approximate properties of the de la Vallée Poussin means for the discrete Fourier-Jacobi sums.
Approximate solutions of equations defined by complex spherical multiplier operators.
Approximation by double Walsh polynomials.
Approximation by Nörlund operators
Approximation by trigonometric polynomials in weighted Orlicz spaces
We investigate the approximation properties of the partial sums of the Fourier series and prove some direct and inverse theorems for approximation by polynomials in weighted Orlicz spaces. In particular we obtain a constructive characterization of the generalized Lipschitz classes in these spaces.
Approximation by weighted means of Walsh-Fourier series.
Approximation diophantienne et ensembles lacunaires
Approximation d'une fonction définie sur une sphère dans une base de fonctions sphériques de Legendre
Approximation et transfert d'opérateurs de convolution
Soient et deux groupes abéliens localement compacts de dual et . Soit un homomorphisme continu d’image dense de dans . Soit ; on prouve un théorème d’approximation des multiplicateurs de et on utilise ce résultat pour démontrer le suivant : soit une fonction continue ; est un multiplicateur de si, et seulement si, est un multiplicateur de .
Approximation in L... Sobolev Spaces on the 2-Sphere by Quasi-Interpolation.
Approximation in weighted generalized grand Lebesgue spaces
The direct and inverse problems of approximation theory in the subspace of weighted generalized grand Lebesgue spaces of 2π-periodic functions with the weights satisfying Muckenhoupt's condition are investigated. Appropriate direct and inverse theorems are proved. As a corollary some results on constructive characterization problems in generalized Lipschitz classes are presented.
Approximation of almost periodic functions by convolution type operators.
Approximation of almost periodic functions by periodic ones
It is not the purpose of this paper to construct approximations but to establish a class of almost periodic functions which can be approximated, with an arbitrarily prescribed accuracy, by continuous periodic functions uniformly on .
Approximation of commutators of singular integrals
Approximation of Distribution Spaces by Means of Kernel Operators.
Approximation of functions from by general linear operators of their Fourier series
We show the general and precise conditions on the functions and modulus of continuity as well as on the entries of matrices generating the summability means and give the rates of approximation of functions from the generalized integral Lipschitz classes by double matrix means of their Fourier series. Consequently, we give some results on norm approximation. Thus we essentially extend and improve our earlier results [Acta Comment. Univ. Tartu. Math. 13 (2009), 11-24] and the result of S. Lal [Appl....
Approximation of functions from by linear operators of conjugate Fourier series
We show the results corresponding to some theorems of S. Lal and H. K. Nigam [Int. J. Math. Math. Sci. 27 (2001), 555-563] on the norm and pointwise approximation of conjugate functions and to the results of the authors [Acta Comment. Univ. Tartu. Math. 13 (2009), 11-24] also on such approximations.
Approximation of functions possessing derivatives of positive orders
Approximation of Gaussian by scaling functions and biorthogonal scaling polynomials.
Approximation of periodic solutions of a system of periodic linear nonhomogeneous differential equations
The present paper does not introduce a new approximation but it modifies a certain known method. This method for obtaining a periodic approximation of a periodic solution of a linear nonhomogeneous differential equation with periodic coefficients and periodic right-hand side is used in technical practice. However, the conditions ensuring the existence of a periodic solution may be violated and therefore the purpose of this paper is to modify the method in order that these conditions remain valid....