Extra
A very similar method was used to generate the following images:

x(t) = sin(a*t + sin(b*t + pi))
y(t) = sin(c*t + sin(d*t))

Right image: (a,b,c,d) = (2,1,3,3)
Video: a,b,c,d = 1,2, or 3

Check out more precision art here.

Day 1: Saturday

Day 2: Sunday