which is presented in Janusz MierczyĆski, Instability in Linear Cooperative Systems of Ordinary Differential Equations.

The matrix A(t) is periodic and piecewise constant alternating between

two values with the same, real, negative spectrum. However, the norm

of the solution does not decay.

Animation by Yash Chandak, Jennifer Li, Autumn Phaneuf, Toby Schwed, and Angelica Simonetti