Sign of a number.

sign([2,0,-3, 2+3j])
numThe input number, complex number, quantity, or matrix.
return valueThe sign of the input.

The input can be any real number, complex number, matrix, or quantity. In case of real numbers and quantites, the result is determined by the sign of the number:
- If num $ <0 $, the result is -1.
- If num $ ==0 $, the result is 0.
- If num $ >0 $, the result is 1.
In case of complex numbers, the result is the normalized complex number numabs(num).

In case of matrices, the operation is done elementwise.