How do you add elements in a matrix (single column, multiple rows) and output to another matrix?

For Example, I have the following:

A1= [1 2 3] (where A1 is a single vertical column, not a single row as it appears here) or in the general sense, A2= [n n+1 n+2] (where A2 is a single vertical column, not a single row as it appears here)

and what I want to do is produce a B such that B= [n n+1-(n) n+2-(n+1)] where the specific element in the matrix is just a subtraction operation between the original corresponding element, and the element directly above it.

[Stephen23]

What would you expect the output to be, for A = [1;2;3] ?

Answer 1

[Stephen23]

Use diff:

 >> [A(1);diff(A)]
 ans =
    1
    1
    1

[James Long]

worked perfectly! thanks Stephen.

Answer 2

[xi]

First of all, A1= [1 2 3] , A1 is one row, not one column. to make it a column, should write A1= [1; 2; 3]

then, try this ------------- A1= [1; 2; 3] B=[A1;0]-[0;A1] B=B(1:end-1) %remove the last element in B