MATLAB: What is the best way to create a vector with a special sequence of subvectors

loopMATLABmatrix manipulation

I have say 100 vectors of equal size (v1 to v100) and I want to create a vector V of the following structure: V=[v1-v2 ;…; v1-v100; v2-v3; … , v2-v100; …. …. …. ; v98-v99 ; v98-v100; v99-v100]. What is the best way to create V?

Best Answer

Store the vectors in one matrix, then you just need to use nchoosek to generate the required indices:
>> M = randi(9,5,3) % each row = one vector
M =
   5   6   9
   9   2   5
   4   5   1
   4   8   2
   9   6   6
>> X = nchoosek(1:size(M,1),2);
>> Z = M(X(:,1),:) - M(X(:,2),:)
Z =
  -4   4   4
   1   1   8
   1  -2   7
  -4   0   3
   5  -3   4
   5  -6   3
   0  -4  -1
   0  -3  -1
  -5  -1  -5
  -5   2  -4
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