The Chen-Lee system is an autonomous quadratic system obtained by adding linear feedback to Euler's equations for a rigid body (Chen and Lee 2004),
 |  |  |
(1)
|
 |  |  |
(2)
|
 |  |  |
(3)
|
where 
, 
, and 
are real parameters. The state variables are 
, 
, and 
, and primes denote derivatives
with respect to time 
. The vector
field is equivariant under changing the signs of any two coordinates. Its divergence is 
, so for 
the flow contracts phase
space volume. In the derivative of the quadratic
form 
, the nonlinear terms cancel, leaving
. Chen and Lee (2004) found a strange attractor numerically for 
, 
, and 
.
The figure shows the 
-projection
of a trajectory with initial state 
over 
.
