poly4root {trio} | R Documentation

## Roots of a Fourth Degree Polynomial

### Description

While `poly4root` computes the (real-valued) roots of a polynomial of fourth degree, `poly4rootMat` can be applied to several polynomials of fourh degree at once by assuming that each row the input matrix contains the coefficients for one of the polynomials.

### Usage

    poly4root(a)

    poly4rootMat(amat)

### Arguments

`a` | a numeric vector of length five specifying the coefficients of the polynomial `a[1]`*x^4 + `a[2]`*x^3 + `a[3]`*x^2 + `a[4]`*x + a[5].
`amat` | a numeric matrix with five columns in which each row contains the five coefficients of a polynomial of fourth degree.

### Value

For `poly4root`, a vector containing the real-valued roots of the polynomial. For `poly4rootMat`, a matrix with four columns in which each row contains the real-valued roots of the corresponding polynomial. If a polynomial has less than four real-valued roots, the remaining entries in the corresponding row are set to `NA`.

### Author(s)

Holger Schwender, holger.schwender@udo.edu

### Examples

    # The roots of
    # 2 * x^4 + 3 * x^3 - x^2 + 5 * x^1 - 4
    # can be determined by
    poly4root(c(2, 3, -1, 5, -4))

[Package trio version 3.24.3 Index]