You can change different mathematic function for x or y coordinate, i.e. Fx(t), Fy(t)
This simulation will plot it for you.
For example: if you enter fx(t)=A*sin(w1*t), fy(t)=B*cos(w2*t)
It will draw Lissajous pattern for you.
The default setting is for someone who want to study variation of Lissajous pattern due to some other noise C*sin(w2*t).