How to obtain the absolute difference between elements in column?

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 columns which gives me

 b= 0  0 -1  1
    0 -1  2 -1

How am I going to do this?

Answer 1

[Walter Roberson]

b = diff(a);

would give the sample output you show.

However, your description asks for the absolute difference, and absolute difference is never negative, so your b does not match your question. To match your question you would abs() the diff()