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Subtract two vectors while shifting them along

Asked by cles
on 10 Jan 2018
Latest activity Commented on by cles
on 19 Jan 2018
Suppose we have two vectors
A = [1 2 3 4];
B = [4 3 2 1];
My goal is to shift them along and get the differences for each position. So for the first combination
[1 2 3 4]
-[4 3 2 1]
the result would be:
C = [0] % difference of 1 and 1
For the second:
C = [-1 1] % differences of 1-2 and 2-1
For the third:
C = [-2 0 -2]
and so on.
I'm stuck on programming a function that works for two vectors of arbitrary sizes, especially how to handle the leading and lagging numbers. For further processing, it would be great to be able to assign NaN to those.
Thanks in advance.

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1 Answer

Answer by Aveek Podder on 17 Jan 2018
Edited by Aveek Podder on 17 Jan 2018
 Accepted Answer

Hi,
You can use length command of Matlab to get the size of the array and write a for loop and proper indexing of the array to get the C vector done. Please have a look at the code below.
L_A = length(A)
L_B = length(B)
for i = 1:min(L_A,L_B)
C = A(1:i) - B((L_B-i+1):L_B)
end

  1 Comment

This worked out, together with using some stuff I found in the implementation of the xcorr function

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