% 得到H
load qpbox1 
lb = zeros(400,1); 
lb(400) = -inf;
ub = 0.9*ones(400,1); 
ub(400) = inf;
f = zeros(400,1);
f([1 400]) = -2;
xstart = 0.5*ones(400,1);
[x,fval,exitflag,output]=quadprog(H,f,[],[],[],[]lb,ub,xstart);