DIRECTIONS: In this applet, you place a sequence
of points p0, p1, p2,
... and then create curve from each set of points p2i-2,
p2i-1, p2i, p2i+1
a cubic curve that passes through the points p2i-2
and p2i which has the derivative at p2i-2
given by p2i-1-p2i-2 and the derivative
at p2i given by p2i+1-p2i