Аннотация:The problem of determining the thermal conductivity coefficient that depends on the temperature is studied. The consideration is based on the Dirichlet boundary value problem for the one-dimensional unsteady-state heat equation. The mean-root-square deviation of the temperature distribution field and the heat flux from the empirical data on the left boundary of the domain is used as the objective functional. An algorithm for the numerical solution of the problem based on the modern approach of Fast Automatic Differentiation is proposed. The case of discontinuous thermal conductivity coefficient is considered. Examples of solving the problem are discussed.