Well, I read a book entitled "3D animation and computer generated images algorithms" ("Algorithmes pour la synthèse d'images et l'animation 3D", a French book in fact, by Rémy Malgouyres), and there's a chapter (several ?) about Bezier curves. I thought that I could use it in a game (but for now I haven't any idea about a game), so first I tried to plot a Bezier curve.
EDIT : the parametric function for a Bezier curve with 4 control points P1 to P4 is :
Q(t) = P1 * (1 - t)3 + P2 * 3t(1 - t)2 + P3 * 3t2(1 - t) + P4 * t3
