Bivariate Mellin convolution operators: Quantitative approximation theorems

In this paper we study some qualitative and quantitative versions of the Voronovskaja approximation formulae for a class of bivariate Mellin convolution operators of type (Twf)(x,y)=∫R+2Kw(tx−1,vy−1)f(t,v)dtdvtv. Moreover we apply the general theory to some particular cases leading to various asymptotic formulae and involving various differential operators.