# Change example (or add exercise) on stability of center when solution curves are non-circular [dynamics]

Issue #38 closed
Richard Murray repo owner created an issue

The current example of stability in Ch 5 (dynamics) uses a linear system with purely circular trajectories to illustrate a center. If we change the second equation from

\dot x_2 = -x_1

to

\dot x_2 = -\lambda x_1

Then the circles will change to ellipses and this might be more illustrative. We should think about this as a possible change in the main text, but if it is too disruptive then it could just be an exercise. Main goal is to get something where $\epsilon$ and \$\delta are different.