In this paper, we study the approximation properties of bivariate summationintegral-type operators with two parameters m, n ∈ N. The present work deals within the polynomial weight space. The rate of convergence is obtained while the function belonging to the set of all continuous and bounded function defined on ([0], ∞)(×[0], ∞) and function belonging to the polynomial weight space with two parameters, also convergence properties, are studied. To know the asymptotic behavior of the proposed bivariate operators, we prove the Voronovskaya type theorem and show the graphical representation for the convergence of the bivariate operators, which is illustrated by graphics using Mathematica. Also with the help of Mathematica, we discuss the comparison by means of the convergence of the proposed bivariate summation-integral-type operators and Szász-Mirakjan-Kantorovich operators for function of two variables with two parameters to the function. In the same direction, we compute the absolute numerical error for the bivariate operators by using Mathematica and is illustrated by tables and also the comparison takes place of the proposed bivariate operators with the bivariate Szász-Mirakjan operators in the sense of absolute error, which is represented by table. At last, we study the simultaneous approximation for the first-order partial derivative of the function. KEYWORDS polynomial weight space, rate of convergence, Szász-Mirakjan-Kantorovich operators MSC CLASSIFICATION 41A25; 41A35; 41A36
INTRODUCTIONFrom 1941 to 1950, there were three authors 1-3 who independently introduced operators, so-called Szász-Mirakjan operators, and studied many properties related to those operators for function belonging to the set of continuous function defined on [0, ∞] (extension of the Bernstein's operators, which is defined on [0, 1]). To the generalization and for the study of approximation properties, some researchers, professors, presented their papers related to Szász-Mirakjan operators concerning some modifications (including extension). Some are as those in the previous studies. [4][5][6][7][8][9][10][11][12][13][14] But still the above mentioned papers and monographs represent only extension or modification of the Szász-Mirakjan operators for functions (f ∈ C[0], ∞), in case if function is integrable then in that condition, modification took place in 1954. First of all, Butzer 15 introduced an integral modification of the Szász-Mirakjan operators (in general, we represent by S n (f; x)) by considering Lebesgue integrable function and were named in Totik 16 as Szász-Mirakjan-Kantorovich operators.