Approximations of the classes MB p,θ r of periodic functions of several variables by polynomials according to the Haar system

Abstract

Some problems of approximation of the classes MBp,θr of periodic functions of several variables by polynomials constructed by the Haar system are investigated. For the functions of these classes, the exact-order estimates of the best m-term approximation by polynomials according to the Haar system and the upper bounds of approximations by step-hyperbolic Fourier–Haar sums are obtained.