Matrix manipulation-changing number of rows & columns of a matrix & keeping all of the elements

Hi, I'm trying to change this simple matrix below:

A(3,4)=[1,2,3,4;5,6,7,8;9,10,11,12]

to look like

A(6,2)=[1,2;3,4;5,6;7,8;9,10;11,12]

All the elements in A(3,4) exist in the new matrix A(6,2).

You can find the new row number (6) of the new matrix by using the formula below (the new matrix A(6,2) is 2 columns & stays that way):

[R,C]=size(A);
R_new=(((C/2)-1)*R)+R;

This is not the real data but, the code for the simplified version will help a lot.

I have already tried to write a code for it using "for loop" but, it didn't work.

Any help is appreciated.

Thank you.

[Greg]

Have you tried reshape?