R: Polynomials

Poly {gsl} | R Documentation

## Polynomials

### Description

Polynomial functions as per the Gnu Scientific Library, reference manual section 6.1. These functions are defined in header file `gsl_poly.h`

### Usage

    gsl_poly(c_gsl,x)

### Arguments

`c_gsl` | Coefficients of the poynomial (`c` in the function definition and the GSL ref manual) starting at the constant term and ending in the highest power; see details section. This argument is called “`c_gsl`” (and not “`c`”) to avoid confusion with R function `c()`
`x` | input: real values

### Details

One must be careful to avoid off-by-one errors. In C idiom, the function evaluates the polynomial

c[0]+c[1]+...+c[len-1]x^(len-1)

where len is the second argument of GSL function `gsl_poly_eval()`.

The R idiom would be

c[1]+c[2]+...+c[len]x^(len-1).

This section is work-in-progress and more will be added when I have the time/need for the other functions here.

### Author(s)

Robin K. S. Hankin

### References

http://www.gnu.org/software/gsl

### Examples

    a <- matrix(1:4,2,2)
    rownames(a) <- letters[1:2]
    (jj <- gsl_poly(1:3,a))

    jj-(1 + 2*a + 3*a^2)  #should be small

[Package gsl version 2.1-6 Index]