This site is supported by donations to The OEIS Foundation.

From OeisWiki

The {{sgn}} mathematical function template for the signum function returns the sign of a number, i.e. -1 for negative real numbers, 0 for zero and +1 for positive real numbers, otherwise returns an error message.

Usage

{{sgn|a real number}}

Valid input

An unformatted real number.

Examples

Examples with valid input

Code	Result	Comment
{{sgn|6}}	1
{{sgn|-0}}	0
{{sgn|0}}	0
{{sgn|+0}}	0
{{sgn|-6}}	-1
{{sgn|-6.9e-45}}	-1
{{sgn|-6.9E+45}}	-1
{{sgn| {{formatnum: 6,500|R}} }}	1	(Cf. Formatted numbers)

Examples with invalid input (returns error message)

Code	Result	Comment
{{sgn|6,500}}	Sgn error: Argument is not a real number	(Cf. Formatted numbers)
{{sgn}}	Sgn error: Argument is not a real number
{{sgn|blob}}	Sgn error: Argument is not a real number
{{sgn|6 blobs}}	Sgn error: Argument is not a real number

Code

{{ifnum| {{{1|NAN}}} 
| {{#ifexpr: ({{{1}}}) = 0
  | 0 
  | {{#ifexpr: abs ({{{1}}}) = ({{{1}}})  
    | 1
    | -1
    }}
  }}
| {{error|Sgn error: Argument is not a real number }} 
}}

See also

• {{abs}} (or the abs operator) to obtain the absolute value of a real number
• {{sgn}} (note that the sgn operator is not supported) to obtain the sign of a real number