A unit vector is any vector v such that norm(v) = 1. For your case of order n=6, you want a 6 element vector v with norm(v) = 1. Some examples of 6-element unit vectors:
v = [1;0;0;0;0;0]
or
v = [1;1;1;1;1;1]; v = v/norm(v);
or
v = rand(6,1); v = v/norm(v);
Any one of these could be used as a suitable starting vector for your problem.
