Example

> compan(1)
        1
> compan(2)
       -2         -3  
        1          0  
> compan(3)
       -2         -3         -4  
        1          0          0  
        0          1          0  
> compan([1,2])
        1
> compan([1,2,3])
       -2         -3  
        1          0  
> compan([2,3,5])
     -1.5       -2.5  
        1          0