Alex's Figure-Eights:

This space curve was produced using the following Maple commands:

> rho:=cos(t):
> x:=rho*tan(t);
> y:=rho*sin(t);
> z:=t^1.9;

                          x := cos(t) tan(t)


                          y := cos(t) sin(t)


                                    1.9
                              z := t

> with(plots):
> spacecurve([x,y,z],t=0..8*Pi,numpoints=1000,
>   axes='NORMAL',thickness=2);