800 = Sinusoidal Ring Wave

I just realise that the fig. 8 knot is just sine wave turned into a unit circle (Sinusoidal Ring Wave). The realisation came after seeing this Demoscene fig. oo knot by scoopex followed by a version that has more cycles:

https://www.pouet.net/prod.php?which=61868

Sinusoidal Ring Wave

https://mathematica.stackexchange.com/questions/69618/sinusoidal-wave-over-a-circle

https://www.shadertoy.com/view/tccczB