Calculating the difference between a vector and time

I'm looking for a way to get this loop to work, basically I need to calculate the difference in a 3x1 vector divide by the difference in time. Does anyone have any suggestion?

t = 2000
n= 0;
for ind = 0:1:t
  n= n+ind;
  S(n) = (diff(x( don't know how to input the value here )))./diff(t(ind));   %x is a three element vector
end

[dpb]

Afraid you're going to have to show us by an example what you have and what you want and how you get from a) to b); I have no idea what you're trying to explain above, sorry...(and apparently the half-dozen or so before me didn't either)

[Nikolaos Zafirakis]

I'm trying to implement the equation above

X vector 3x1

t: time

[dpb]

dxdt = diff(x)./diff(t);

[Nikolaos Zafirakis]

So, the diff command wont work for this because if

A = [1 1 2 3]

diff(A)

= [ 0 1 1 2]

where I would need the ouput to be

=[1 0 1 1]

because

Delta_A(1) = 1 - 0 = 1 % first element - no element

Delta_A(2) = 1 - 1 = 0 % second element - first element

Delta_A(3) = 2 - 1 = 1 % third element - second element

Delta_A(4) = 3 - 2 = 1 % four element - third element

[Star Strider]

If you are ‘padding’ ‘A’ with an initial 0, you need to tell MATLAB.

MATLAB does many things well, although it is sadly deficient when it comes to mind-reading.

Try this:

A = [1 1 2 3];
dA = diff([0 A])

producing:

dA =
     1     0     1     1

NOTE — You need to do similar ‘padding’ for your time vector.

Answer 1

[Omer N]

Try this:

A = [1 1 2 3];
A-[0,A(1:end-1)]
ans =

     1     0     1     1