function so3 = vector2so3(vector)
so3 = zeros(3,3);
so3(1,2) = -vector(3);
so3(1,3) = vector(2);

so3(2,1) = vector(3);
so3(2,3) = -vector(1);

so3(3,1) = -vector(2);
so3(3,2) = vector(1);