I've been using matlab for solving a quadratic optimization problem, using a factor structured hessian, say I have a covariance matrix H and I wrote it as H=A+B*B'.
Then I have a small piece of code to calculate the
hessianf=@f;
options = optimset('HessMult', hessianf);
y1 = quadprog(A, r, [], [], [], [], [], [], [], options, B);
with
function H=f(A,x,B)
H=A*x+B*(B'*x);
end
The above process is just following http://www.mathworks.com/help/toolbox/optim/ug/brn4nlc.html
However, matlab says "H must be specified explicitly for the active-set algorithm: cannot use HessMult option.".
I got very confused at where the problem is. Could anyone give me some suggestion?