Editing Sign function (section)

{{Short description|Function returning minus 1, zero or plus 1}}
{{Redirect|Sgn||SGN (disambiguation)}}
{{distinguish|Sign relation|Sine function}}

[[Image:Signum function.svg|thumb|Signum function <math>y = \sgn x</math>]]

In [[mathematics]], the '''sign function''' or '''signum function''' (from ''[[wikt:signum#Latin|signum]]'', [[Latin language|Latin]] for "sign") is a [[Function (mathematics)|function]] that has the value {{math|&minus;1}}, {{math|+1}} or {{math|0}} according to whether the [[Sign (mathematics)|sign]] of a given [[real number]] is positive or negative, or the given number is itself zero. In [[mathematical notation]] the sign function is often represented as <math>\sgn x</math> or <math>\sgn (x)</math>.<ref name=":0">{{Cite web|title=Signum function - Maeckes|url=http://www.maeckes.nl/Signum%20functie%20GB.html|access-date=|website=www.maeckes.nl}}</ref>