Before revision: The Routh criterion To derive Routh's criterion, first we will use a different notation to differentiate between the even and odd terms of : Now we have: Therefore, if is even, and if is odd: Now observe that if is an odd integer, then by (3) is odd.
After revision: The Routh criterion To derive Routh's criterion, first we 'll use a different notation to differentiate between the even and odd terms of : Now we have: Therefore, if is even, and if is odd: Now observe that if is an odd integer, then by (3) is odd.