cos(x) sin(x)(2 X+ 4) x+4x+3(x+4x+3) 原函数及一阶导数图: X1=0:01:5 03 y=subs(f,x, x1) 026 y1=subs(fl, x,x1) >>plot(x1,y2x1,y1,:2) 0.15 0.1 更高阶导数: tic, diff(f, x, 100); toc elapsed time 0.06 4.6860cos(x) sin(x) (2 x + 4) --------------- - ------------------- 2 2 2 x + 4 x + 3 (x + 4 x + 3) 原函数及一阶导数图： >> x1=0:.01:5; >> y=subs(f, x, x1); >> y1=subs(f1, x, x1); >> plot(x1,y,x1,y1,‘:’) 更高阶导数： >> tic, diff(f,x,100); toc elapsed_time = 4.6860