The identity element

Create and test for the identity element

Usage

is.id(x)
id(n)
# S3 method for class 'free'
is.id(x)

Arguments

x

Object of class free

n

Strictly positive integer

Details

Function id() returns a vector of n free objects, all of which are the identity element. Do not ask what happens if \(n=0\).

Function is.id() returns a Boolean indicating whether an element is the identity or not. The identity can also be generated using as.free(0).

Author

Robin K. S. Hankin

Examples

id()
#> [1] 0
as.free(0)   # convenient R idiom for creating the identity
#> [1] 0

x <- rfree(10,3)
stopifnot(all(x == x + as.free(0)))
stopifnot(all(is.id(x-x)))