Presents the basics of functional analysis, as well as elements of variational equations (on the basis of bi-linear forms), including the Vishik-Lax-Milgram theorem and of generalized solutions of eliptic problems. In terms of functional analysis, such problems of computational mathematics are considered as extremal of problems of approximation theory of various types - the theory of numerical integration, variational methods of minimization of quadratic functional, and Galerkin and Ritz methods of finding solutions to operator equations. Also covered are: the general theory of iteration methods, Chebyshen iteration methods, composition method, along with some elements of nonlinear analysis. Sobolev spaces and embedding theorems are also introduced.