Sign

sign(Real)

sign(Complex)

Given a real number $x$, returns its sign: $\text{sign}\left(x\right)=\left\{\begin{array}{l}0,\text{if }x=0\\ 1,\text{if }x>0\\ -1,\text{if }x<0\end{array}\right.$

Given a complex number $z$, returns $\text{sign}\left(z\right)=\left\{\begin{array}{l}0,\text{if }z=0\\ \frac{z}{||z||},\text{if }z\ne 0\end{array}\right.$

Sign0, Negative?, Positive?