I just wanted to know what the variation of $U_n = (-1)^n$ is. I think it is constant but the regular methods do not work. Since $U_{n+1} - U_n$ is either negative (which means $U$ is descending) or equal to 0 (which means $U$ is constant). Furthermore, $\frac{U_{n+1}}{U_n} < 0$ which shouldn't be possible. In my understanding you cannot convert this sequence in a function and study the variation of this function. If you could enlighten me on this...
$\begingroup$
$\endgroup$
2
-
1$\begingroup$ How do you define the variation of a sequence? $\endgroup$– jorikiCommented Dec 8, 2019 at 10:51
-
$\begingroup$ Who knows what you want to do with it, but (total) variation normally adds the absolute values of the changes: $\sum_n |U_{n+1}-U_n|$. $\endgroup$– conditionalMethodCommented Dec 8, 2019 at 10:52
Add a comment
|