Because it's also useful in studying curves, pi helps us understand periodic or oscillating systems

Well, sine just keeps oscillating, between negative 1 and plus 1, and so does cosine.

One way to do this is to set an oscillating measurement between 2 and 0.

That coil is connected to an R.F. amplifier that creates a high frequency oscillating magnetic field.

This draws smoothly shaded oscillating oval patterns that look something like vapor trails or neon tubes. Written by Shane Smit 1999.

Of course, as we accumulate error that gets corrected for and we steer down, but eventually we get into this sort of oscillating behavior.

Oscillating between starving myself for months at a time, hmm, until I hit 85 pounds and then, of course, the pendulum swinging in the opposite direction, bingeing completely and utterly out of control.