The approximation of continuous periodic functions of two variables by Faward sums

An estimate is given of the magnitude of the exact upper bound of the errors of double Faward sums on classes of continuous periodic functions, and asymptotic equations are found in the case of the classes $H_{A,B}^{\alpha,\beta}$ for these quantities, expressed in terms of the exact upper bounds of the errors of Faward sums on the classes $H_A^\alpha$ and $H_B^\beta$ of functions of one variable.