Fwd: manipulate block matrices with maxima

Hello,

I want to know if there exist a package to manipulate blocks of matrices,
for example,
from matrices
sx:matrix([0,1],[1,0]);
sz:matrix([1,0],[0,-1]);

create a matrix with shape

[ sz  sx ]
[ sx  sz ]

matrix([1,0,0,1],[0,-1,1,0],[0,1,1,0],[1,0,0,-1])

thanks


Mauricio Matera