The nonlinear system is: $\dot{x}_1=\frac{5}{2}-2x_2-\frac{3}{2}x_1+x_2x_1$ and $\dot{x}_2=x_1-\frac{5}{2}$.
My problem is trying to find the Lyapunov function for this system, if one exists. I've been using the Sums of Squares Method, but it doesn't work for this system. Even MatLab's been throwing up errors when I tried using SOSTools. Any ideas?