# Flows Along Conic Sections

Here’s a cute bit of math I figured out recently. It probably doesn’t have much practical application, at least not for graphics programmers, but I thought it was fun and wanted to share it.

First of all, everyone knows about rotations: they make things go in circles! More formally, given
a plane to rotate in and a center point, rotations of any angle will preserve circles in the same
plane and with the same center. By “preserve circles”, I mean that the rotation will send every
point on the circle to somewhere on the same circle. The individual points move, but the *set*
of points comprising the circle is invariant under rotation.