R: Coerce polynom or polylist objects to function.

as.function.polynom {PolynomF} | R Documentation

## Coerce polynom or polylist objects to function.

### Description

Since `polynom` objects are represented as functions, `as.function.polynom` simply removes the `class` attribute. The function `as.function.polylist` produces allows all polynomials on the list to be evaluated simultaneously at the same argument value.

### Usage

    ## S3 method for class 'polynom'
    as.function(x, variable = "x", ...)
    ## S3 method for class 'polylist'
    as.function(x, ...)

### Arguments

`x` | A `polynom` or `polylist` object.
`variable` | A character string giving the name to be used for the formal argument of the resulting function, (for `as.polynom` only).
`...` | Not currently used.

### Details

Since `polynom` objects are already stored as functions, `as.function.polynom` is rarely needed and may be replaced by `unclass`. An explicit call to `as.function.polynom`, however, will generate a slightly faster version of the function as an unrooled loop, and does allow the user to specify a different name for the formal argument to be used.

Since arithmetic on polynomials is provided, both of these functions may be evaluated at a `polynom` object as well as a numeric argument.

### Value

An `R` function implementing the evaluation.

### Author(s)

Bill Venables

### References

None

### Examples

    x <- polynom()
    H <- polylist(polynom(1), x)
    for(j in 2:5)
        H[[j+1]] <- x*H[[j]] - (j-1)*H[[j-1]]
    H5 <- as.function(H)
    H5(-4:4)
    H5(x+1)

[Package PolynomF version 1.0-1 Index]