“…It has been shown that models with fractional order derivatives are more adequate than integer order models.The main reason is that fractional derivatives are an excellent tool for describing memory and hereditary properties of various materials and processes. An examples of real systems, we can mention here electrochemical cells, capacitors with irregular (fractal) electrodes, viscoelastic media, disordered semiconductors, plasma and similar media [2,3,5,6,13,16,23,26,28,29,30,31,33,34,35,36,32]. The paper [26] considers the problem of fractional optimal control described by a system of linear differential equations, where its cost function is expressed as the ratio of convex and concave functions.…”