[new_x, new_y] in the function definition, or when you actually call this function, does not mean that you will get one variable out with new_x in column 1 and new_y in column 2, like you would if you did this:
c = [columnVector1 columnVector2];
It behaves differently. When calling or defining a function, it means that you get two variables returned and they are separate - not concatenated. If you specify only one, it will give you the left most return variable and any to the right of it are "thrown away" because you did not supply a variable in your calling routine to accept them. I hope that explains it.
