The constant term

Get and set the constant term of a freealg object

# S3 method for class 'freealg'
constant(x)
# S3 method for class 'numeric'
constant(x)
# S3 method for class 'freealg'
constant(x) <- value
is.constant(x)

Arguments

x

Object of class freealg

value

Scalar value for the constant

Details

The constant term in a free algebra object is the coefficient of the empty term. In a freealg object, the map including \(\emptyset\longrightarrow v\) implies that \(v\) is the constant.

If x is a freealg object, constant(x) returns the value of the constant in the multivariate polynomial; if x is numeric, it returns a constant freealg object with value x.

Function is.constant() returns TRUE if its argument has no variables and FALSE otherwise.

Setting the coefficients of the empty freealg returns the zero (empty) object.

Author

Robin K. S. Hankin

Examples

p <- as.freealg("1+X+Y+xy")

constant(p)
#> [1] 1
constant(p^5)
#> [1] 31

constant(p) <- 1000
p
#> free algebra element algebraically equal to
#> + 1000 + Y + X + xy