MATLAB: How to subtract elements in a matrix from each other

matrix subtraction

Hello there!
I want to find out how I can subtract the elements of a matrix from one another in a particular order. Lets say that I have the following matrix:
 matrix_1 = [30 39 42; 10 15 22; 1 5 7]
This matrix represents the running total counts of some function. To get the counts for each individual cell, I want to subtract the element in a cell from the one before it. In this case, the solution will do something like this:
 matrix_2 = [30-22 39-30 42-39; 10-7 15-10 22-15; 1 5-1 7-5]
in order to produce:
 matrix_3 = [8 9 12; 3 5 7; 1 4 2]
Does anyone know of a way I can automize this process so I don't need to calculate this by hand?
>> A = [30 39 42; 10 15 22; 1 5 7]A =   30   39   42   10   15   22    1    5    7>> flipud(reshape([A(end,1),diff(reshape(flipud(A).',1,[]))],size(A,2),[]).')ans =   8   9   3   3   5   7   1   4   2