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weyl (version 0.0-7)

horner: Horner's method

Description

Horner's method

Usage

horner(W,v)

Arguments

W

Weyl object

v

Numeric vector of coefficients

Author

Robin K. S. Hankin

Details

Given a formal polynomial

$$p(x) = a_0 +a_1+a_2x^2+\cdots + a_nx^n$$

it is possible to express \(p(x)\) in the algebraically equivalent form

$$p(x) = a_0 + x\left(a_1+x\left(a_2+\cdots + x\left(a_{n-1} +xa_n \right)\cdots\right)\right)$$

which is much more efficient for evaluation, as it requires only \(n\) multiplications and \(n\) additions, and this is optimal.

See Also

ooom

Examples

Run this code
horner(x,1:5)
horner(x+d,1:3)

2+x+d |> horner(1:3) |> horner(1:2)

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