2D Array Manipulation / Script

I am looking to write a simple MATLAB script that will take any 2D array and double its size by duplicating every entry in the horizontal, vertical, and diagonal direction. The catch is I can not use for-loops. I have been thinking about using repmat(), but am unsure how this could translate to my problem.

For example, if I have a matrix A = [1 4 7 ; 8 9 3], then the result should be:

A=[
  1 1 4 4 7 7 
  1 1 4 4 7 7 
  8 8 9 9 3 3 
  8 8 9 9 3 3
  ]

I hope I am articulating my thoughts well. Any help or tips would be greatly appreciated.

Answer 1

[Azzi Abdelmalek]

%method1

 res=cell2mat(arrayfun(@(x) repmat(x,2,2),A,'uni',false))

%or method 2

 [n,m]=size(A)
B=zeros(n,2*m);
B(:,1:2:2*m)=A;B(:,2:2:2*m)=A
C=zeros(2*n,2*m);
C(1:2:2*n,:)=B;C(2:2:2*n,:)=B

[Jason Kossis]

Thanks for the help!

[Matt Fig]

Method 3:

kron(A,ones(2))

Answer 2

[Matt Fig]

You can also use expand, which is written to be more general and memory efficient.

A = [1 4 7 ; 8 9 3],
expand(A,[2,2])

ans =

       1     1     4     4     7     7
       1     1     4     4     7     7
       8     8     9     9     3     3
       8     8     9     9     3     3