Duplicate every element of a matrix to NxN elements

Hello, I need to duplicate all the elements of an MxM matrix to NxN elements so the resulting matrix has the size (M*N)x(MxN). For example,

A =

1 2

3 4

I want the matrix B to be duplicated from A's elements such that

B =

1 1 2 2

1 1 2 2

3 3 4 4

3 3 4 4

I have been using the following loops to accomplish this:

for k = 1:M

for j =1:M

B((j-1)*N+1 : j*N, (k-1)*N+1 : k*N) = A(j,k);

end

end

My question is: is there a more efficient way of doing it? If M and N are not large, it's not a big deal. But when they are large, the nested loop can take quite a long time.

Answer 1

[Stephen23]

>> M = [1,2;3,4];
>> kron(M,[1,1;1,1])
ans =
   1   1   2   2
   1   1   2   2
   3   3   4   4
   3   3   4   4

[Xinbing Liu]

Thank you very much. This solution works very well.

Answer 2

[KSSV]

A = [1     2
     3     4 ] ;
[nx,ny] = size(A) ;
B = cell(nx,ny) ;
for i = 1:nx
    for j = 1:ny
        B{i,j} = repelem(A(i,j),nx,ny) ;
    end
end
B = cell2mat(B)