Example

> a = rand(5,5)
 a =
     0.44      0.741      0.842      0.599      0.239  
    0.685      0.313      0.652      0.455      0.465  
    0.129      0.759      0.386      0.658      0.546  
     0.79      0.151      0.583      0.232      0.801  
    0.868      0.325      0.205      0.797      0.247  
> svd(a).sigma
 sigma =
      2.6      0.835      0.624      0.442     0.0475  
> rank(a)
        5
> b = [a,a;a,a];
> svd(b).sigma
 sigma =
 matrix columns 1 thru 6
      5.2       1.67       1.25      0.884      0.095   1.63e-16  

 matrix columns 7 thru 10
 6.15e-17   2.93e-17   1.04e-17   1.45e-18  
> rank(b)
        5