This site is supported by donations to The OEIS Foundation.

# Template:Sgn

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 }}
}}

```