M=
    0.515     -0.55      1.37 
    0.474    -0.124    -0.917 
   -0.493     -2.01    -0.929 

qrm.A=
    0.856     0.758     0.851 
    0.743      1.95       0.3 
   -0.613     -1.43     -1.66 

b=
    0.393     -0.16    0.0798 
x=
   0.0376    -0.148     0.213 
M*x=
    0.393     -0.16    0.0798 
M*x-b
 5.55e-17 -2.78e-17         0 
M*x==b ? : 1
MI=
    0.624      1.18    -0.243 
   -0.322   -0.0706    -0.405 
    0.366    -0.472    -0.071 

MI*M=
        1 -1.67e-16 -5.55e-17 
        0         1 -5.55e-17 
-2.08e-17         0         1 

M*MI=
        1 -1.11e-16  4.16e-17 
 5.55e-17         1  5.55e-17 
 1.67e-16  5.55e-17         1 



M=
    0.515     -0.55      1.37 
    0.474    -0.124    -0.917 
   -0.493     -2.01    -0.929 
    0.393     -0.16    0.0798 

qrm.A=
    0.942     0.622     0.807 
    0.743         2     0.357 
   -0.613     -1.43      1.67 
     0.43    -0.232     -3.02 

b=
   -0.428    0.0222    -0.117    -0.532 
x=
    -0.44     0.222    -0.132 
M*x=
    -0.53    -0.114    -0.106    -0.219 
M*x-b
   -0.102    -0.137    0.0115     0.313 
M*x==b ? : 0
MI=
    0.442     0.934    -0.223      0.56 
   -0.292     -0.03    -0.408   -0.0931 
    0.387    -0.444   -0.0734   -0.0648 

MI*M=
        1 -2.36e-16 -2.57e-16 
-2.08e-17         1 -6.42e-17 
-1.04e-17 -3.64e-17         1 

M*MI=
    0.918    -0.109   0.00921     0.251 
   -0.109     0.853    0.0123     0.336 
  0.00921    0.0123     0.999   -0.0283 
    0.251     0.336   -0.0283     0.229