How can I resize or scale up a matrix without for loop?

Hello,

I have matrix A:

 A = 

 1    2

 3    4

and want to resize it to be matrix B. Matrix B should be like this:

 B = 
 1 1 1 2 2 2
 1 1 1 2 2 2
 1 1 1 2 2 2
 3 3 3 4 4 4
 3 3 3 4 4 4
 3 3 3 4 4 4

My method is an ugly one like this:

A        = [1 2;3 4];
scale    = 3;
B        = []; 
[M N]    = size(A);
for i = 1:M
    for j = 1:N
        B((((i-1)*scale)+1):(i*scale),(((j-1)*scale)+1):(j*scale)) = A(i,j);
    end
end

So, how can I resize or scale matrix up without using for loop?

Thanks for advice,

K. Pituso

Answer 1

[Walter Roberson]

B = kron(A, ones(3,3));

[Phillip]

As of R2015a you can also use

B = repelem(A,3,3);