Michael S's Double-Helix and More:

The Double-Helix:

"The Double-Helix" was produced using the following Maple commands:

> x:=sin(Pi*t)*cos(t)/Pi;
> y:=sin(Pi*t)*sin(t)/Pi;
> z:=t/2/Pi/20;

                             sin(Pi t) cos(t)
                        x := ----------------
                                    Pi


                             sin(Pi t) sin(t)
                        y := ----------------
                                    Pi


                                       t
                            z := 1/40 ----
                                       Pi

> with(plots):
> spacecurve([x,y,z],t=0..100*Pi,numpoints=10000,
>   axes='NORMAL',orientation=[45,85]);

Yarn:

"Yarn" was produced using the following Maple commands:

> x:=sin(Pi*t)*cos(t)/Pi;
> y:=sin(Pi*t)*sin(t);
> z:=ln(t)*sin(t);

                             sin(Pi t) cos(t)
                        x := ----------------
                                    Pi


                        y := sin(Pi t) sin(t)


                          z := ln(t) sin(t)

> with(plots):
> spacecurve([x,y,z],t=0..100*Pi,numpoints=10000,
>  axes='NORMAL',orientation=[45,75]);