In the problem of the parameter estimation by a minimization/maximization of a multi-extreme function the Hermite expansion is considered instead of the Taylor series. The symmetrization of the function around the objective point "u" of position of the global maximum simplifies the view of their expansion in the Hermite's polynomials-series. The analysis of extremal points of the forth coefficient ("kurtosis","excess") of this Hermite-series allows one to get the approach to this point "u".