LISSAJOUS

x = sin(at + δ), y = sin(bt)

a: 3
b: 2
δ: 0.78
trail:
1:1 1:2 2:3 3:2 3:4 5:4 5:6 7:6 9:8
These curves appear on oscilloscopes when two signals at different
frequencies are fed to the X and Y axes. Integer ratios make closed curves.
The phase δ rotates the figure in a way that feels like breathing.