identity: The identity element

Description

Create and test for the identity element

Usage

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

Arguments

Object of class free

Strictly positive integer

Details

Function id() returns a vector of 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).

Examples

Run this code

# NOT RUN {
id()
as.free(0)   # convenient R idiom for creating the identity

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

# }

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