:
These equations have two equilibrium solutions. The first, which we label a, occurs at
The second, which we label b, occurs at
The location in the phase plane of these equilibrium points is shown in Figure 4.17.
The motion in the vicinity of each equilibrium point is analyzed by
finding the eigenvalues 
and eigenvectors 
,
of the derivative matrix of 
, 
,
at each fixed point of the flow.
At the point a we find
