Focal Values for Quadratic Systems with Four Real Singular Points

摘要

In this paper, focal values (Lyapunov coefficients) for quadratic dynamicalsystems having 4 real singular points in the finite part of real phase plane are constructed. The method to compute focal values is fully justified in the original manner, without making use of existence of a Lyapunov integral for systems under consideration. Conditions for the occurrence of a 3rd-order focus or a center are derived. The analysis was done by means of the author's original computer software based on the MAPLE V system and the FORM symbolic manipulation package. (Copyright (c) 1994 by Faculty of Technical Mathematics and Informatics, Delft, The Netherlands.)