# Poly

From gsl v1.9-2
0th

Percentile

##### Polynomials

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

Keywords
array
##### 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_gs
x
input: real values
##### Details

One must be careful to avoid off-by-one errors. In C idiom, the function evaluates the polynomial $$c[0]+c[1]x+c[2]x^2+\ldots+c[\mathrm{len}-1]x^{\mathrm{len}-1}$$ where len is the second argument of GSL function gsl_poly_eval().

The Ridiom would be $$c[1]+c[2]x+c[3]x^2+\ldots+c[\mathrm{len}]x^{\mathrm{len}-1}.$$

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

##### References

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

• Poly
• poly
• gsl_poly
##### 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
Documentation reproduced from package gsl, version 1.9-2, License: GPL-2

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