Mathematically self-contained, this text for advanced undergraduates and graduate students combines two important methods -- the finite element method and the variational method -- into the framework of functional analysis. It does so in order to explain potential applications to approximation of nonhomogeneous boundary-value problems for elliptic operators. 1980 edition.A marriage of the finite-differences method with variational methods for solving boundary-value problems, the finite-element method is superior in many ways to finite-differences alone. This self-contained text for advanced undergraduates and graduate students is intended to imbed this combination of methods into the framework of functional analysis. 1980 edition.