This calculation allows obtaining approximation of data using generalized Pade (rational) functions. Coefficients of these functions are derived from the condition that the fitting curve passes through several points. The number of points should be equal to the amount of unknown function coefficients. For this purpose the interval, where the data should be approximated, is divided into the corresponding number of subintervals (cells). Coordinates of points are chosen using two different ways: 1) as mean values of given (experimental) data on each subinterval (cell) or 2) as the coordinates of given points from these subintervals. The main condition for calculation of coefficients of Pade functions leads to the system of simultaneous linear equations. The accuracy of approximation can be managed by changing values of three main parameters: number of coefficients of Pade function; given accuracy, and correlation coefficient of data fitting. The obtained result is thus represented as a relatively simple formula.