On the mean square of the error term for the two-dimensional divisor problems(II)

Let $\Delta(a,b;x)$ denote the error term of the general two-dimensional divisor problem. In this paper we shall study the relation between the discrete mean value $\sum_{n\leq T}\Delta^2(a,b;n)$ and the continuous mean value $\int_1^T\Delta^2(a,b;x)dx$.