Matrices, change diagonal elements in nxn matrix from 3nx3 matrix.

Hi,

I would like to know how to reshape multidimanrtional matrix into a matrix with diagonal elements.

I have A(n,3,3) matrix that I would like to transform to B(n,m) matrix. Elements for B matrix must be diagonal and are defined as B((j-1)*3+1:j*3, (i-1)*3+1:i*3)=([A(n,1,:) A(n,2,:) A(n,3,:);A(n+1,1,:) A(n+1,2,:) A(n+1,3,:);A(n+2,1,:) A(n+2,2,:) A(n+2,3,:)]), where n is number of rows in A matrix.

B((j-1)*3+1:j*3, (i-1)*3+1:i*3)=squeeze(A(j,:,:)) does not work. It gives me back randomly placed elements from A into B.

An example of what I need is:

A(n,3,:)= [1,2,3;

4,5,6;

7,8,9;

10,11,12;

13,14,15;

16,17,18;.....] transformed into

B(n,m)=[1,2,3,0,0,0,0.....,0;

4,5,6,0,0,0,0.....,0;

7,8,9,0,0,0,0.....,0;

0,0,0,10,11,12;0.....,0;

0,0,0,13,14,15,0......,0;

0,0,0, 16,17,18,0......,0;

........]

Thank you.