You need to change the last line of the program to this:
You will then get an error, because in the program you have mixed literal and vector subscripts where you want vector subscripts. For example, the assignment of alpha0 and X0. Also the assignment of Xi+1 based on Xi. many others too. You need to track all of these down and change the literal subscript to a vector subscript. Then each of the variables is a vector (of the same length), and augment will convert them to the columns of a matrix.