MATLAB: How to acess elements of a matrix with round indexes without loops

Question

For exemple if I have a matrix that is 3×3

     1 1 1
A =  1 1 1
     1 1 1

I want to multiply elements with round indexes by 2 so it look like this:

    1 2 1
A = 2 1 2
    1 2 1

Answer 1

A(2:2:end)=A(2:2:end)*2