We present optimal convergence results for the mth derivative of a function by sequences of linear operators. The usual convergence is replaced by -summability, with being a sequence of infinite matrices with nonnegative real entries, and the operators are assumed to be m-convex. Saturation results for nonconvergent but almost convergent sequences of operators are stated as corollaries.
"Optimal Simultaneous Approximation via -Summability." Abstr. Appl. Anal. 2013 1 - 5, 2013. https://doi.org/10.1155/2013/824058