It has been proven that to any electric circuit there exists a corresponding two pairs of conjugate linear vector spaces. One of these pairs is generated by a homological group, while the other is cohomological. A new method of analysis of mechanical and electric circuits is proposed, which consists of representing the main variables and matrices of oscillatory circuits in terms of many-dimensional tensor objects. A solution is obtained for the problem of defining eigenvalues of pure-loop and pure-node circuits. This title looks at problems associated with the theory of engineering systems.