“…In particular, Ali and Abdullah [4] derived a group explicit method derived from a skewed five-point finite difference approximations where the proposed method was shown to be more efficient in CPU timings than the existing schemes based on the standard five-point difference stencil. With the realization that preconditioning technique is essential for the improvement in the performance of iterative methods, research on preconditioners has moved to center stage in recent years ( [7], [8], [9], [10], [11], [12]). Recently, Ali and Saeed [13] proposed a (I + K)-type preconditioning matrix in block form and applied it to the original system obtained from the four point Explicit Decoupled Group (EDG) method for solving the coupled system of elliptic partial differential Eqs.…”