polynom {spatstat.model}

Polynomial in One or Two Variables

Description

This function is used to represent a polynomial term in a model formula. It computes the homogeneous terms in the polynomial of degree n in one variable x or two variables x,y.

Usage

  polynom(x, ...)

Arguments

x

A numerical vector.

...

Either a single integer n specifying the degree of the polynomial, or two arguments y,n giving another vector of data y and the degree of the polynomial.

Details

This function is typically used inside a model formula in order to specify the most general possible polynomial of order n involving one numerical variable x or two numerical variables x,y.

It is equivalent to poly(, raw=TRUE).

If only one numerical vector argument x is given, the function computes the vectors x^k for k = 1, 2, ..., n. These vectors are combined into a matrix with n columns.

If two numerical vector arguments x,y are given, the function computes the vectors x^k * y^m for k >= 0 and m >= 0 satisfying 0 < k + m <= n. These vectors are combined into a matrix with one column for each homogeneous term.

Value

A numeric matrix, with rows corresponding to the entries of x, and columns corresponding to the terms in the polynomial.

Author(s)

Adrian Baddeley [e-mail], Rolf Turner [e-mail] and Ege Rubak [e-mail].

See Also

poly, harmonic

Examples

   x <- 1:4
   y <- 10 * (0:3)
   polynom(x, 3)
   polynom(x, y, 3)