This demo includes a single graphical display window that displays the
conical helix X(t) = (at*cos(t),at*sin(t),bt). You can change t0,
a, b, and X(t) and choose whether or not to show
the entire curve and the position vector X(t0) in the
control window. You can also choose whether or not to show the cone on
which X(t) lies.