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# signum fn (SignumFn)

(SignumFn number) denotes the sign of number. This is one of the following values: -1, 1, or 0.

## Ontology

SUMO / NUMERIC-FUNCTIONS

## Class(es)

 class

inheritable relation

unary function

signum fn

## Coordinate term(s)

absolute value fn  abstraction fn  arc cosine fn  arc sine fn  arc tangent fn  back fn  begin fn  begin node fn  cardinality fn  ceiling fn  complement fn  cosine fn  cut set fn  denominator fn  end fn  end node fn  extension fn  floor fn  front fn  future fn  generalized intersection fn  generalized union fn  giga fn  imaginary part fn  immediate future fn  immediate past fn  initial node fn  integer square root fn  kilo fn  list length fn  magnitude fn  mega fn  micro fn  milli fn  minimal cut set fn  nano fn  numerator fn  organization fn  past fn  path weight fn  pico fn  power set fn  predecessor fn  principal host fn  probability fn  property fn  rational number fn  real number fn  reciprocal fn  round fn  sine fn  skin fn  square root fn  successor fn  tangent fn  tera fn  terminal node fn  wealth fn  when fn  year fn

## Type restrictions

integer SignumFn(real number)

## Related WordNet synsets

polarity, sign
having an indicated pole (as the distinction between positive and negative electric charges); "he got the polarity of the battery reversed"; "charges of opposite sign"

## Axioms (4)

If "number1 mod number2" is equal to number, then "the sign of number2" is equal to "the sign of number".
```(=>
(equal
(RemainderFn ?NUMBER1 ?NUMBER2)
?NUMBER)
(equal
(SignumFn ?NUMBER2)
(SignumFn ?NUMBER)))```

If number is an instance of nonnegative real number, then "the sign of number" is equal to or "the sign of number" is equal to .
```(=>
(instance ?NUMBER NonnegativeRealNumber)
(or
(equal
(SignumFn ?NUMBER)
1)
(equal
(SignumFn ?NUMBER)
0)))```

If number is an instance of positive real number, then "the sign of number" is equal to .
```(=>
(instance ?NUMBER PositiveRealNumber)
(equal
(SignumFn ?NUMBER)
1))```

If number is an instance of negative real number, then "the sign of number" is equal to .
```(=>
(instance ?NUMBER NegativeRealNumber)
(equal
(SignumFn ?NUMBER)
-1))```