oo. 5) D The most difficult part in the application ofthis theorem in practical situations is the verification of condition (ii). 3 The Mu/tigrid Method In the two-grid method we have to solve exactly one coarse grid problem FH cH = dH in each iteration step. In the multigrid method (MGM) we solve this problem only approximately by applying a few iteration steps of the same MGM on the coarser level.
Wesseling, P,: Multigrid acceleration of an iterative method with application to transonic potential flow. (To appear,)  Ortega, J. , Rheinboldt, C. : On discretization and differentiation of operators with applications to Newton's method. SIAM J. Numer. Anal. 3, 143 -156 (1966). : The difference correction method for nonlinear two-point boundary value problems. - Techn. Rep. CS 18, Compo Sc. , California, 1965. : Accelerating the convergence of discretization algorithms. SIAM J. Numer. Anal.