这样更好些,无需知道dy【如果很复杂,就显得很有用了】:
function hh
%global dy
y='x*sin(x)';
ezplot(y),grid
dy=diff(y)
x0=[-5 -2 0 2 5];
fsolve(@myfun,x0)
function f=myfun(x)
global dy
f=subs(dy);
结果:
dy =
sin(x)+x*cos(x)
Optimization terminated: first-order optimality is less than options.TolFun.
ans =
-4.9132 -2.0288 0 2.0288 4.9132