最优化方法—黄金分割法求最小值_Matlab实现

% 此程序解决最优化方法中的黄金分割问题
% 目标函数Func()
% 函数区间[a,b]
% eps为目标区间长度
Func = @ (x) 2*x*x-5*x+1;
a = 1;
b = 6;
eps = 1;
i = 0;
x1 = a+0.382*(b-a);
x2 = a+0.618*(b-a);
f1 = Func(x1);
f2 = Func(x2);
fprintf("i = %d\n",i);
fprintf("a = %f  b = %f\n",a,b);
fprintf("x1 = %f  x2 = %f\n",x1,x2);
fprintf("f1 = %f  f2 = %f\n",f1,f2);
fprintf("abs(b-a) = %f\n",abs(b-a));
fprintf("\n")
while 1
    if(f1>f2)
        a=x1;
    elseif(f1==f2)
        a = x1;
        b = x2;
    else
        b = x2;
    end
    x1 = a+0.382*(b-a);
    x2 = a+0.618*(b-a);
    f1 = Func(x1);
    f2 = Func(x2);
    i=i+1;
    fprintf("i = %d\n",i);
    fprintf("a = %f  b = %f\n",a,b);
    fprintf("x1 = %f  x2 = %f\n",x1,x2);
    fprintf("f1 = %f  f2 = %f\n",f1,f2);
    fprintf("abs(b-a) = %f\n",abs(b-a));
    fprintf("\n")
    if(abs(b-a)<eps)
        break;
    end
end
x_res = 0.5*(a+b);
f_res = Func(x_res);
fprintf("x* = %f,f* = %f",x_res,f_res)