function mod_mxm_test ( )

  A = [ ...
     6, 24,  1; ...
    13, 16, 10; ...
    20, 17, 15 ];

  B = [ ...
     8,  5, 10; ...
    21,  8, 21; ...
    21, 12,  8 ];

  n = 26;

  C = A * B

  Cmod = mod_mxm ( A, B, n )

  return
end

