Ding Yanheng;Lin Qun
Journal of Systems Science and Complexity. 1989, 2(1): 54-069.
The Ritz projections of the elliptic problem
-\partial_i (a_(ij)(\partial _ju)+c_0u=f in Ω, u=0 on \partial Ω,
and the quasilinear eiliptic problem
-\partial (a_i(x,Du))+a_0(x,Du)=0 in Ω, u=0 on \partial Ω
with linear finite elements admit an asymptotic error expansion, respectively, for certain classes of“uniform” meshes. This provides the theoretical justification for the use of Richardson extrapolation for increasing the accuracy of the scheme from O(h~2) to O(h~4 |ln h|).