Create a matrix from another one with an history window of 3 columns

Could someone help me with my problem.

I've got an original 2 by 25 matrix and I want to create a new 2 by 25 matrix with the same columns than the original one. But I want them reorganized such that a given column (:,n) in the new matrix is different from the columns (:,n:n+2) of the original matrix.

I've struggled to do that as Ifind a way using loops that need a lot of if statement to control for special cases... Is there someone with a simple(r) method to do that?

[KALYAN ACHARJYA]

Can you elaborate with example?

[Julien Benistant]

Here is an example,

a= [1,2,3];

b = [4,8,12];

A = combvec(a,b);

B = A(:,randperm(size(A,2)));

B =

1 2 1 3 1 2 3 2 3

12 8 4 4 8 4 8 12 1

What I wan't is a new matrix C to be equal to (C should be the same size than B but I shorten it for the example):

C =

3 1 3

4 12 12

with C(:,1) = B(:,4) being different from B(:,1:3), C(:,2) = B(:,1) being different from B(:,2:4) etc...

Hope the example is clear.

[Stephane Dauvillier]

OK? sorry I don't know what you mean

[Julien Benistant]

Sorry I wasn't clear but I found a simple solution, I post it here in case of someone need help:

A= [1,3,5,7,8];

B = [4,12,20,28,32];

C = combvec(A,B);

S = randi([4 21],1);

V = [C(:,S:end), C(:,1:S-1)];

Basically I've just created a new matrix (V) randomly lagged (S) compared to the original one (C) !

Best,

Answer 1

[Stephane Dauvillier]

You can try the function diff:

A = magic(5);
B = diff(A,[],2)

But B will have n-1 column what do you want for the extra column ?