几何变换 ●(Xy)→(X1y) ●X=f1(×y),y=f2(Xy) 曲线C:X=X(t),y=y(t)→ 曲线C′:X=f1(X(t),y(t), y=f2 x(ty(t)几何变换 •(x,y) → (x’,y’) •x’=f1 (x,y), y’=f2(x,y) • 曲线C: x=x(t),y=y(t) → 曲线C’: x=f1(x(t),y(t)), y=f2(x(t),y(t))