Signum
From specialfunctionswiki
The signum function (also called the sign function) is the function $$\mathrm{sgn}(x)=\left\{ \begin{array}{ll} 1 &; x > 0 \\ 0 &; x = 0 \\ -1 &; x < 0 \end{array} \right.$$
The signum function (also called the sign function) is the function $$\mathrm{sgn}(x)=\left\{ \begin{array}{ll} 1 &; x > 0 \\ 0 &; x = 0 \\ -1 &; x < 0 \end{array} \right.$$
