Powell法最优化设计matlab程序

function output=Divide（fxmn）
if nargin<4n=1e-6;end
if nargin<3m=0;end
step=n;
t0=m;ft0=subs（f{x}{t0}）;
t1=t0+step;ft1=subs（f{x}{t1}）;
if ft0>=ft1
    t2=t1+step;ft2=subs（f{x}{t2}）;
    while ft1>ft2
        t0=t1;
        %ft0=ft1;
        t1=t2;ft1=ft2;
        step=2*step;t2=t1+step;ft2=subs（f{x}{t2}）;
    end
else 
    step=-step;
    t=t0;t0=t1;t1=t;ft=ft0;
    %ft0=ft1;
    ft1=ft;
    t2=t1+step;ft2=subs（f{x}{t2}）;
    while ft1>ft2
        t0=t1;
        %ft0=ft1;
        t1=t2;ft1=ft2;
        step=2*step;t2=t1+step;ft2=subs（f{x}{t2}）;
    end
end
output=[t0t2];