“…More precisely, mesh residual function r = (r , r ) was de ned by the equalities r ,ij = p ,ij − h − (u i+ ,j − u ij ), r ,ij = p ,ij − h − (u i,j+ − u ij ) in a mesh node (ih, jh), and r L = h i,j (r ,ij + r ,ij ) / . We used the stopping criterion r L h (see [8] on the stopping criterion for Uzawa-type iterative methods).…”