特色：
This book discusses the accuracy of various finite element approximations and how to improve them with the help of extrapolations and superconvergence’s post-processing technique. The discussion is based on asymptotic expansions for finite element and finally reduce to the technique of integration by parts, embedding theorems and norm equivalence lemmas. Also, the book is devoted to explain the origin of theorems to make what is written correspond with what is originally in our mind.