There are certainly formulas for solving polynomials numerically up to 4th
degree non-iteratively, but you will almost certainly get better results
using iterative methods.
Even the much more trivial formula for the 2nd degree (quadratic) is tricky
to implement correctly and accurately, see:
* George Forsythe, How do you solve a quadratic equation?
* Yves Nievergelt, How (Not) to Solve Quadratic Equations
Hope this helps.
-s
On Tue, Jan 5, 2010 at 10:11 AM, Mads Jeppe Tarp-Johansen <
s02m...@math.ku.dk> wrote:
> To R-helpers,
>
> R offers the polyroot function for solving mentioned equations iteratively.
>
> However, Dr Math and Mathworld (and other places) show in detail how to
> solve mentioned equations non-iteratively.
>
> Do implementations for R that are non-iterative and that solve mentioned
> equations exists?
>
> Regards, Mads Jeppe
>
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