function [ok] = blkbidiag_symm_mul_ok()
ok = true;
% -------------------------------------------------------------
% You can change these parameters
m = 2;
n = 3;
N = 4;
% -------------------------------------------------------------
% Define the problem
rand('seed', 123);
rand('seed', 123);
Hdia = rand(n, n, N);
Hlow = rand(n, n, N);
Ddia = zeros(n, n, N);
for k = 1:N
dk = rand(n, n);
Ddia(:,:,k) = dk'*dk;
end
Hfull = ckbs_blkbidiag_mul(Hdia, Hlow, eye(n*N));
Dfull = ckbs_blkdiag_mul(Ddia, eye(n*N));
HDHfull = Hfull * Dfull * Hfull';
[r, s] = ckbs_blkbidiag_symm_mul(Hdia, Hlow, Ddia);
HDH = ckbs_blktridiag_mul(r, s, eye(n*N));
check = HDH - HDHfull;
ok = ok & ( max(max(abs(check))) < 1e-10 );
return
end