How to obtain the absolute difference between elements in a row?

Hi I have

 a=  4     3     2     1
     4     3     1     2
     4     2     3     1

I want to know the absolute difference between elements for each of the rows which gives me

 b= 1 1 1
    1 2 1 
    2 1 2

How am I going to do this? Thank you.

Answer 1

[Guillaume]

b = abs(diff(a, 1, 2))