R: Polynomial construction

polynom {PolynomF} | R Documentation

## Polynomial construction

### Description

Functions to construct polynomial objects and check class membership

### Usage

    polynom(a = c(0, 1), ..., eps = 0)

    polynomial(a = c(0, 1), ..., eps = 0)

    as_polynom(a)

    is_polynom(a)

    polylist(...)

    is_polylist(x)

    as_polylist(x)

### Arguments

`a` | A `polynom` object, or a numeric vector of coefficients (in "power series" order) or a vector object which can be coerced to one.
`...` | Additional arguments, currently ignored.
`eps` | A small non-negative tolerance to check for zero components.
`x` | An object of class `"polylist"`, at least potentially.

### Value

A polynomial object.

### Examples

    (s <- polynomial())
    (p <- polynomial(c(1, 5, 4, 1)/11))
    oldPar <- par(mar = c(5,5,2,2)+0.1)
    plot(p, xlim = 0:1, ylim = 0:1, type = "n", bty="n",
         xlab = "s", ylab = expression({P^(n)}(s)))
    lines(s, limits = 0:1)
    P <- p
    for(j in 1:7) {
      lines(P, col = j+1, limits = 0:1)
      P <- p(P)
    }
    lines(P, limits = 0:1, col = 9)
    (r <- Re(solve((p-s)/(1-s))))
    arrows(r, p(r), r, par("usr")[3], lwd = 0.5,
           length = 0.125, angle = 15)
    text(r, 0.025, paste("r =", format(r, digits = 3)))
    leg <- sapply(0:8, function(x) bquote({P^(.(x))}(s)))
    legend("topleft", legend = as.expression(leg),
           lty = "solid", col = 1:9, bty = "n", ncol=3)
    par(oldPar)
    rm(leg, oldPar, p, P, r, s, j)

[Package PolynomF version 2.0-3 Index]