How to subtract a vector element without a loop?

I am totally new to vectorised language, so please enlighten me. For below (Octave), I want to subtract element i from the element before it (i-1), ie they are cumulative and i want to see the incremental. How can I do it without using a loop.

Code:

>> x
x =

   30
   50
   55
   68
   85
   86

>> for i=rows(x):-1:2
x(i,1) = x(i,1) - x(i-1,1);
end
>> x
x =

   30
   20
    5
   13
   17
    1