Approximation by algebraic polynomials on rectangles
A direct theorem for approximation by algebraic polynomials in two variables with different degrees in each variable in L-p- metric (1 less than or equal to p less than or equal to infinity) on rectangles is proved, and the dependence of the constants on various parameters is studied.
algebraic polynomials in two variables quasi-interpolant spline jackson type theorem weighted sobolev space h-p version of fem