Matrix X
     3.70000000     -2.10000000      7.40000000     -1.00000000 
     4.10000000      0.00000000      3.90000000      4.00000000 
    -2.50000000      1.90000000     -0.40000000      7.30000000 
     1.50000000      9.80000000     -2.10000000      1.10000000 

Inverse of X
    -0.15613535      0.27856000     -0.17406776      0.00029026 
     0.07956310     -0.08691703      0.04180094      0.11098579 
     0.22744144     -0.14910111      0.10868682      0.02766552 
    -0.06171667      0.10984958      0.07244980     -0.02727139 

X * inverse of X
     1.00000000     -0.00000000      0.00000000      0.00000000 
     0.00000000      1.00000000      0.00000000      0.00000000 
    -0.00000000     -0.00000000      1.00000000     -0.00000000 
    -0.00000000      0.00000000      0.00000000      1.00000000