Example

> a = [1,2,3,4,5]
 a =
        1          2          3          4          5  
> diff(a)
        1          1          1          1  
> b = [1,2,4,7,11]
 b =
        1          2          4          7         11  
> diff(b)
        1          2          3          4  
> diff(diff(b))
        1          1          1  
> diff(b,2)
        1          1          1  
> diff(b,3)
        0          0  
> c = [1,1,1;
>      2,2,2;
>      3,4,5;
>      4,7,11]
 c =
        1          1          1  
        2          2          2  
        3          4          5  
        4          7         11  
> diff(c)
        1          1          1  
        1          2          3  
        1          3          6  
> diff(c,2)
        0          1          2  
        0          1          3  
> diff(c,3)
        0          0          1