Time reversal of an autonomous differential equation
= Time reversal of an autonomous differential equation
{title2=$\dot z=F(z)\ \longmapsto\ \dot z=-F(z)$}
If $z(t)$ solves an <autonomous differential equation>, $w(t)=z(-t)$ solves the equation with negated <vector field>. The trajectories and <equilibrium points> stay in place but their orientations reverse; stable and unstable directions interchange. A <saddle equilibrium> remains a saddle, and a clockwise <centre equilibrium> becomes counterclockwise.