Multivariate quasi-projection operators Qj(f,φ,φ˜), associated with a function φ and distribution/function φ˜, are considered. The is supposed to satisfy the Strang-Fix conditions compatibility condition φ˜. Using technique based on Fourier multipliers, we study approximation properties of such for functions f from anisotropic Besov spaces Lp 1≤p≤∞. In particular, upper lower estimates Lp-error...

We study the asymptotic behavior of the roots of polynomials given by a linear summation method for partial sums of the Fourier series. DOI: 10.1134/S0001434610110106