permutations: sgn – R documentation

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sgn

Sign of a permutation

Description

The sign of a permutation is +/-1 depending on whether it is even or odd

Usage

sgn(x)
is.even(x)
is.odd(x)

Arguments

`x`	permutation object

Details

Coerces to cycle form

Author(s)

Robin K. S. Hankin

Examples

sgn(id)  # always problematic

sgn(rperm(10,5))

x <- rperm(40,6)
y <- rperm(40,6)


stopifnot(all(sgn(x*y) == sgn(x)*sgn(y)))   # sgn() is a homomorphism


z <- as.cycle(rperm(20,9,5))
z[is.even(z)]
z[is.odd(z)]

permutations

The Symmetric Group: Permutations of a Finite Set

v1.0-9

GPL-2

Authors

Robin K. S. Hankin [aut, cre] (<https://orcid.org/0000-0001-5982-0415>), Paul Egeler [ctb] (<https://orcid.org/0000-0001-6948-9498>)

Initial release

sgn