Convergence of derivatives for certain mixed Szasz--Beta operators (Q2497335)

The authors introduced a general class of summation-integral type operators.The behaviour of those operators is similar to that of operators considered by \textit{V. Gupta, M. K. Gupta} and \textit{V. Vasishta} [Simultaneous approximation by summation integral type operators. J. Nonlinear Funct. Anal. Appl. 8, 399-412 (2003)],but the main difference is that the new operators reproduce not only the constant ones but linear functions also. Some direct results are obtained (a point-wise rate of convergence,an asymptotyc formula of Voronovskaya type and an estimate in simultaneous approximation).