Solutions of the 2m(th)-order nonlinear differential equation
U-(2m) = f(x, u, u',..., u((2m-1)))
satisfying Lidstone boundary conditions are differentiated with respect to
both boundary points and boundary values. The resulting functions are then
shown to be solutions of the corresponding variational equation satisfying
specific boundary conditions. (C) 2000 Elsevier Science Ltd. All rights res
erved.