The sign of a real number, also called sgn or signum, is for a negative number (i.e.,
one with a minus sign ""), 0 for the number zero, or
for a positive
number (i.e., one with a plus sign ""). In other words, for real ,
The sign function is implemented in the Wolfram Language for real
as Sign[x].
For nonzero complex numbers, Sign[z]
returns , where is the complex modulus
of .
can also be interpreted as an unspecified
point on the unit circle in the complex plane (Rich and Jeffrey 1996).
Bracewell, R. "The Sign Function, ." In The
Fourier Transform and Its Applications, 3rd ed. New York: McGraw-Hill, pp. 61-62,
1999.Rich, A. and Jeffrey, D. "Function Evaluation on Branch Cuts."
SIGSAM Bull., No. 116, 25-27, June 1996.