Weighted approximation of continuous functions of three variables in a tetrahedron with variable boundary by Bernstein-Chlodowsky polynoms

This thesis consists of four sections. The first section is devoted to introduction and some essential definitions and theorems. Moreover, some function spaces and the general properties of linear positive operators are introduced and some of the approximation theorems for these spaces are given. In the second and third sections the properties of approximation by Bernstein-Chlodowsky polynomials for functions of one variable and two variables are investigated respectively, and the rates of approximations are analysed by the usual modulus of continuity and the weighted modulus of continuity. In the fourth chapter which is the final chapter of the thesis; the properties of approximation by Bernstein-Chlodowsky polynomials for continuous functions of three variables in a tetrahedron with variable boundary. The rates of approximations are analysed by the usual modulus of continuity and the weighted modulus of continuity. The effectiveness of this approximation is presented graphically.