[en] Development of numerical methods for calculation of equipment operation modes, in particular for NPPs, leads to thorough analysis of local characteristics in space of the objects considered obtaind on the basis of two- and three-dimensional approximations. Except the possibility of more qualified estimation of equipment serviceability, the numerical methods, representing the information as a set of concrete values depending on the initial data, don't give the evident representation about the degree of some factor influence on the remelts obtained that decreases essentially the usefulness of the numerical methods for estimation of the perspective of equipment structure modifications, for analysis of permissible operation modes, for optimization of the construction and operation modes. Thus, the problem on description of equipment characteristics obtained by the numerical methods (or as a result of natural experiment) as analytical functions (or table functions) of the initial data (factors) arises. A way of data table processing is described. Data present a form of latin square-type allowing to construct a linear analytical model. As an example, the table of values of thermal efficiency of a heat exchanger is considered. The values are obtained by numerical calculation (two-dimensional approximation for fields of flow and heat exchange characteristics) for series of fixed values of three parameters (the flow rate of heating and heated media and power). The function approximating the data obtained and determined by the methods described is also given