Causal
h[n] = h(t) = 0 , For all n < 0 & t < 0
- Also, if output depends only on past OR present but NOT future values of "t" or "n".
Stable
$ \sum_{k=-\infty}^\infty |h[n]| < \infty $ , $ \int_{-\infty}^{\infty}|h(t)| < \infty. $
Memoryless
- If output depends only on present values of "t" or "n".
