How to double the size of a matrix and propagate its elements in Matlab?

Question

suppose I have a matrix like this:

a = 
    1    2
    3    4

I want to double the size of matrix and create something like this:

Answer 1

use kron - Kronecker tensor product:

kron(a,ones(2))


ans =
 1     1     2     2
 1     1     2     2
 3     3     4     4
 3     3     4     4