matrice..
> theta:=arctan(-1/sqrt(5),2/sqrt(5)):phi:=arctan(sqrt(5)/3,2/3):
> m:=simplify(evalm(T3d(-1,0,0)&*Rotz(-theta)&*Roty(-phi)&*S3d(1,1,-1)&*Roty(phi)&*Rotz(theta)&*T3d(1,0,0)));
>
![m := matrix([[1/9, 4/9, -8/9, 0], [4/9, 7/9, 4/9, 0...](images/geo677.gif)