valid 4-by-4 test matrix (A=sparse(magic(4)) in MATLAB)                |magic4  
             3             1             1             1
iua                        4             4            16             0
(26I3)          (40I2)          (26I3)              
  1  5  9 13 17
 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
  0  5  9  4  2 11  7 14  3 10  6 15 13  8 12  1