Abstract. In the spaces $S^p$ of functions of several variables, $2\pi $-periodic in each variable, we study the approximative properties of operators $A^\triangle _\varrho,r$ and $P^\triangle _\varrho,s$, which generate two summation methods of multiple Fourier series on triangular regions. In particular, in the terms of approximation estimates of these operators, we give a constructive description of classes of functions, whose generalized derivatives belong to the classes $S^pH_\omega $.
AMS Subject Classification
(1991): 42B05, 26B30, 26B35
classes $H_\omega $,
Received October 30, 2012. (Registered under 87/2012.)