This book gives an excellent presentation of the mathematics behind the FEM that can also be understood by engineers. A very strong point is the intensive discussion of errors, not only the discretization error but all possible errors that might occur during the complete idealization process.



By practical reasons, the theory presented is mostly limited to two-dimensional problems but results can easily transferred to 3-dimensional problems.



Although the book is on theory, it has been of extremely practical value to me. There is nothing more practical than a good theory.