Perhaps your problem is one of integer values, 0 through 20 for each of your seven variables. If you cannot vectorize your function evaluations, then you are left with the prospect of evaluating the objective function 21^7 ~ 2e9 times, which would be quite time-consuming, but straightforward.
xbest = [0,0,0,0,0,0,0]
fmin = fun(xbest);
for i1 = 0:20
for i2 = 0:20
...
for i7 = 1:20
x = [i1,i2,i3,i4,i5,i6,i7]
f = fun(x)
if f < fmin
xbest = x
fmin = f
end
...
end
If you can vectorize your function evaluation, say x(5), x(6), and x(7), then you will have a much smaller set of indices to loop over. You would, in that example, need to evaluate 21^3 = 9261 function values at once and take the minimum. You would loop over that 21^4 = 194481 times.
Good luck,
Alan Weiss
MATLAB mathematical toolbox documentation
