Property: if $ E_{\infty} $ is finite, then $ P_\infty $ equals to zero.
Proof:
$ E_\infty = \int^{+\infty}_{-\infty}|x(t)|^2 dt $
$ P_\infty = \displaystyle\lim_{T\to\infty} \dfrac{1}{2T} \int^{+T}_{-T}{|x(t)|^2}{dt} $
We see from the equations above that,
$ P_\infty = \displaystyle\lim_{T\to\infty} \dfrac{E_\infty}{2T} $
For $ E_{\infty} < {\infty} $, we got that,
$ P_\infty = \displaystyle\lim_{T\to\infty} \dfrac{E_\infty}{2T} = 0 $
if E_{\infty} is finite, then P_\infty equals to zero- Ali Alyoussef
from the formula, it can be seen that
P = the limit of (E/2T) when T goes to infinity.
and if E is a fixed value < infinity
=> P = E/infinity which will guarantees that we will have a result of zero for P.
