repeat
    input "Enter size of matrix: " n
until n > 0

dim identity(n, n) // all zero by default

// enter 1s in diagonal elements
for i =  1 to n
    identity(i, i) = 1
next i

// print identity matrix if n < 40
print

if n < 40 then
    for i = 1 to n
        for j = 1 to n
            print identity(i, j);
        next j
        print
    next i
else
    print "Matrix is too big to display on 80 column console"
end if