The numerical flowgram method first proposed in Ref.[1] is further developed for a quantitative scaling analysis of an isolated critical point — with the focus on critical point of  liquid-gas (LG) transition.  This method avoids any fitting procedure routinely used in the literature where a position of the point is treated as fitting parameters. Thus, the accuracy of the method is solely determined by the statistical errors of a Binder cumulant and its derivatives for simulated system sizes. Using this approach the position of the critical point [2], the critical indices as well as the position of the coexistence line [3] for the 2D LG transition are determined with the combined error of 1-2% [2,3]. This resolves the long standing controversy about the universality of the LG criticality  — the indices are consistent with the Onsager values [2]. The method is also applied to the phi^4 2D model with the odd terms, and it is found that the scaling dimension of the lowest most potentially relevant term, phi^5, is the same as the linear one. Thus, we conjecture that all higher odd terms are equivalent to the linear one close to the fixed point [2].

[1] A.B.Kuklov, N.V.Prokof’ev ,B.V.Svistunov, M.Troyer, Ann. of Phys. 321(2006) 1602;

[2] Max Yarmolinsky and Anatoly Kuklov, Phys. Rev. E 96, 062124 (2017);

[3] Max Yarmolinsky and Anatoly Kuklov, to be submitted.