Matrix inverse.

random square matrix A:
    -0.503     -0.779     -0.066      0.543 
     0.315     -0.134     -0.292      0.888 
    -0.797      0.285     -0.943     -0.504 
     -0.36       0.98      0.364       0.31 

A^-1:
    -0.833      0.517     -0.297     -0.505 
    -0.546       0.24      0.183      0.567 
     0.362     -0.756     -0.702      0.388 
     0.332      0.731    -0.0978      0.393 

check: A*A^-1:
         1   1.11e-16  -1.04e-16   1.11e-16 
  2.78e-16          1   8.33e-17   1.67e-16 
  5.55e-17          0          1  -8.33e-17 
  2.78e-17   1.94e-16  -7.63e-17          1 

A*A^-1 = Id, test passed

check: A^-1*A=
         1  -5.55e-17  -2.78e-17          0 
 -5.55e-17          1  -1.11e-16   5.55e-17 
   2.5e-16  -5.55e-17          1  -5.55e-17 
 -8.33e-17  -5.55e-17  -2.78e-17          1 

A^-1*A = I, test passed