Avoiding for-loops with subsequent elements in arrays

Hi, given this

x = [0 10 20 30];
y = [20 10 10 15];

could you suggest a more compact (and faster) way to perform this operation?

A(1) = (y(1) - y(2)) / (x(2) - x(1));
for i = 2 : 4
   A(i) = (y(i-1) - y(i)) / (x(i) - x(i-1));
end 

Thanks to everyone!

Answer 1

[madhan ravi]

-[0, diff(y) ./ diff(x)]

[James Tursa]

You forgot to fill the (1) spot.

[Sim]

Thanks Madhan, it is a nice solution :) but it looks like the first term should not be zero...?! ....maybe in this was we get the entire array:

[A(1) -diff(y) ./ diff(x)]

[madhan ravi]

eh... well looks like you edited your question after I answered. Before since you didn’t preallocate A MATLAB fills the “first” element with “zero” so...

[Sim]

Yes, sorry, I forgot one line....