MATLAB: How to replace elements of a matrix with the scaled identity

Question

I have some arbitrary square matrix, for example:

A = [ 1 2 3; 4 5 6; 7 8 9 ];

I would like to replace each element with its scalar value multiplied by the identity of some size n. For example, taking n=2, I want to get:

B = [ 1 0 2 0 3 0;

0 1 0 2 0 3;

4 0 5 0 6 0;

0 4 0 5 0 6;

7 0 8 0 9 0;

0 7 0 8 0 9 ];

Since the size n is constant, the matrix B is guaranteed to have consistent dimensions. Is there a quick way to do this without having to loop over the elements of A and find the corresponding indices of B to place the identity?

Answer 1

B=kron(A,eye(n))