Subtract rows in matrix using loop

Hi, I have a 11 x 3541 matrix. For each column I want subtract; row1 from row1 then,row1 from row 2 then, row2 from row 3 and so on. I have tried using a loop but it doesn't work.

for i= 0:12
  mono_am = UVI_all_am(1+i,:) - UVI_all_am(i+1-i,:);
end

Answer 1

[Stephen23]

Use diff:

diff(UVI_all_am,1,1)

And stick a row of zeros along the top if you really need row1 - row1.

[David du Preez]

How can I add the row off zeros to the first line if the matrix has already been made ?

[Stephen23]

 X = diff(UVI_all_am,1,1);
 X = [zeros(1,size(X,2));X];

[David du Preez]

Thanks