R: Lagrange interpolation polynomial

poly_calc {PolynomF} | R Documentation

## Lagrange interpolation polynomial

### Description

Calculate the Lagrange interpolation polynomial, or list of polynomials, given a set of (x, y) points to fit

### Usage

    poly_calc(x, y, tol = sqrt(.Machine$double.eps), lab = dimnames(y)[[2]])

    poly_from_zeros(...)

    poly_from_roots(...)

    poly_from_roots(...)

    poly_from_values(x, y, tol = sqrt(.Machine$double.eps), lab = dimnames(y)[[2]])

### Arguments

`x` | A numeric vector of x-points at which the y-values are specified.
`y` | Either a numeric vector of the same length as `x` or a numeric matrix with rows matching the length of `x`. If `y` is missing (not specified) then a polynomial with zero at `x` is returned.
`tol` | A numeric tolerance for duplicated `x` values.
`lab` | A character string vector of names for the list result when `y` is a matrix.
`...` | A list of specified zeros (for subsidiary functions)

### Value

An interpolation polynomial, or list of interpolating polynomials.

### Examples

    (p <- poly_calc(0:5)) ## same as poly_from_zeros(0:5)
    (p <- poly_calc(0:5, exp(0:5)))
    plot(p)
    curve(exp, add = TRUE, col = "red")

[Package PolynomF version 2.0-3 Index]