The multiple approximation solutions are obtained when some of the six necessary parameters are forcibly equated to zero. Thus, there are obtained approximation implementations, which could be called – partial ones.

From the combinatorics point of view, it is clear that 63 variants of partial approximations could be constructed. Nevertheless, some combinations of zeroed parameters lead to the functions that have no sense, and the others have the infinity values.

Thus, the senseless functions are screened out initially, and all other solutions are checked out for the finiteness, and when leaving for infinity, they are screened out too. On the average, 10–20 solutions are obtained for each approximation opening day and each data series.

*** The W.H.O. data on confirmed cases until February 15 are normalized with a constant coefficient, calculated as the ratio of the number of clinically diagnosed to the number of lab-tested for February 15.