x, y, z, t, u, v, w, a, b, c, d, e, 
-a*x-u*w+u*x
-a*y-t*w+t*y
-b*v-c*x+v*x
-b*t-c*z+t*z
-d*v-e*y+v*y
-d*u-e*z+u*z
