12[4−3−21]\frac{1}{2}\left[\begin{array}{rr}4 & -3 \\-2 & 1\end{array}\right]21[4−2−31]
12[4−2−31]\frac{1}{2}\left[\begin{array}{rr}4 & -2 \\-3 & 1\end{array}\right]21[4−3−21]
−12[4−3−21]-\frac{1}{2}\left[\begin{array}{rr}4 & -3 \\-2 & 1\end{array}\right]−21[4−2−31]
−12[4−2−31]-\frac{1}{2}\left[\begin{array}{rr}4 & -2 \\-3 & 1\end{array}\right]−21[4−3−21]