Signal Energy
Signal Energy expended from $ t_1\! $ to $ t_2\! $ for CT functions is given by the formula $ E = \int_{t_1}^{t_2} \! |x(t)|^2\ dt $
The total signal energy for a signal can be found by taking the limits for the integral $ t_1\! $ and $ t_2\! $ as $ -inf\! $ and $ \inf\! $ respectively
For DT signals, the total energy is given by the formula $ E_{inf} = \sum^{inf}_{n=-inf} |x[n]|^2 \! $
Signal Power
For CT functions, the power of a signal from $ t_1\! $ to $ t_2\! $ is given by the function $ P_{avg}=\frac{1}{t_2-t_1} \int_{t_1}^{t_2} |x(t)|^2\ dt \! $
The total signal power is given by the function $ P_{inf}=\lim_{t->inf} \frac{1}{2t} \int_{-t}^{t} |x(t)|^2\ dt \! $
$ \sum^{N}_{n=-N} $
Total signal power for DT signals is given by the formula $ P_{inf} = \lim_{N->inf} \frac{1}{2N+1} \sum^{N}_{n=-N} |x[n]|^2\! $
