A1 = diag( [ 0.95, 0.95, 0.8, 0.8 ] );



A2 = blkdiag( ...

         [ 0.95 1; ...

            0  0.95 ], 0.8, 0.8 );



A1p = eye(size(A1));

A2p = eye(size(A2));

n1 = [];

n2 = [];

maxk = 100;

for k = 1:maxk,

   A1p = A1p * A1;

   A2p = A2p * A2;

   n1 = [ n1, norm(A1p) ];

   n2 = [ n2, norm(A2p) ];

end



semilogy(1:maxk,n1,'b-',1:maxk,n2,'r-');

makelarge

grid on