DIRECTIONS:   In this applet, you create a rational Bezier curve, described as

(Σ B_iⁿ(t) λ_ip_i)/ (Σ B_iⁿ(t) λ_i)

by placing control points p_i = (x_i,y_i) on the screen, which are stored as points in space as (1,x_i,y_i). The weights λ_i are initially set as 1, and are modified by using the A and Z keys. The A key decreases the weight and the Z key increases the weight.