Question

Find the value of sgn(-1) + sgn(0) + sgn(1), where sgn(x) is the signum function.

Answer 1

$sgnf\left(x\right)=\{\begin{array}{cc}1,& ifxgt0\\ 0,& ifx=0\\ -1& ifx<0\end{array}$
is called the signum function.
The domain of the signum function is R and the range are the set {-1, 0, 1}
The graph of signum function is

sgn(-1) = -1
sgn(0) = 0
sgn(1) = 1
Therefore sgn(-1) + sgn(0) + sgn(1) = -1 +0 +1 = 0