\(y = z\)

\(y = \max(0, z)\)

\(y = \log(1 + \exp(z))\)

\(y = \begin{cases}1 & z > 0 \\ 0 & z \le 0\end{cases}\)

\(y = \dfrac{1}{1 + \exp(-z)}\)

\(y = \dfrac{\exp(z) - \exp(-z)}{\exp(z) + \exp(-z)}\)