Reshaping a 2D matrix to a 3D one with specific ordering

Hello,

I have a nxn matrix that i would like to reshape into a (2 x 2 x :) matrix without using any loops and in this way but with reshape:

an example with "n = 4" and:

A = [1 2 3 4;...

5 6 7 8;...

9 10 11 12;...

13 14 15 16]

gives: B(: , : ,1) = [1 2;

5 6]

B(: , : ,2) = [3 4;

7 8]

B(: , : ,3) = [9 10;

13 14]

B(: , : ,4) = [11 12;

15 16]

Thanks !!

Answer 1

[Bruno Luong]

A = [1   2  3  4;...
5   6   7   8;...
9  10  11 12;...
13 14 15 16]

[m n] = size(A);
B = permute(reshape(A,[2 m/2 2 n/2]),[1 3 4 2]);
B = B(:,:,:)

[Loïc Ballesteros]

It works well, thanks.

[Bruno Luong]

Please accept the answer

[Loïc Ballesteros]

Just one more question: after that i do several transformation on B (rotations) and at the end i want to reshape B in order to get a similar matrix to A (same size and elements ordered in the same way). How could i do it ?

[Bruno Luong]

AA = reshape(ipermute(reshape(B,[2 2 n/2 m/2]), [1 3 4 2]), [m n])

[Loïc Ballesteros]

Thank you