# How to analyze and evaluate a system of differential equations without equilibrium points?

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Cola on 8 Oct 2021
Edited: Cola on 11 Oct 2021
There is a system of differential equations containing more than two variables, and the differentials of the variables cannot all be zero at the same time, and the equilibrium point may not exist. Now we can calculate the system to show its phase plane by using Runge-Kutta methods (Ode45 in Matlab). But phase plane is not suitable for analysis and evaluation and there is no quantitative index. Can one give some advice to analyze and evaluate this system? Thank you.
where where c is a constant.
Cola on 10 Oct 2021
Edited: Cola on 11 Oct 2021
@Star Strider @James Tursa Thank you. I can calculate the system to show its phase plane by using Ode45 in Matlab. I find that the area of the curve around the attractive point maybe a way to evaluate the system of differential equations.
For example. I draw the phase plane by Data.mat as shown below, and (0,20) is the point of attraction.
Now I want to calculate the area as shown below by Data.mat.
The whole area can be divided to these parts.
Cola on 11 Oct 2021