The orthoprojection widths of some classes of periodic functions of two variables with a given majorant of the mixed moduli of continuity

摘要

This paper deals with the orthoprojection widths of classes of periodic functions of two variables with a given majorant of the mixed moduli of continuity of order l that contains logarithmic factors as well as powers. In several cases we find the exact orders of the orthoprojection widths of these classes of functions.