From: couturie Date: Thu, 14 Jan 2016 16:09:53 +0000 (+0100) Subject: new X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/kahina_paper2.git/commitdiff_plain/2bf774646b9314d29be9cbe5d5e6771c391ae7c7?ds=inline new --- diff --git a/paper.tex b/paper.tex index 93a0366..81a5e46 100644 --- a/paper.tex +++ b/paper.tex @@ -661,19 +661,29 @@ EA: z^{k+1}_{i}=z_{i}^{k}-\frac{\frac{p(z_{i}^{k})}{p'(z_{i}^{k})}} {1-\frac{p(z_{i}^{k})}{p'(z_{i}^{k})}\sum_{j=1,j\neq i}^{j=n}{\frac{1}{(z_{i}^{k}-z_{j}^{k})}}}, i=1,. . . .,n \end{equation} -contain 4 steps, start from the initial approximations of all the roots of the polynomial,the second step initialize the solution vector $Z$ using the Guggenheimer~\cite{Gugg86} method to assure the distinction of the initial vector roots, +This methods contains 4 steps. The first step consists of the initial +approximations of all the roots of the polynomial. The second step +initializes the solution vector $Z$ using the Guggenheimer +method~\cite{Gugg86} to ensure the distinction of the initial vector +roots. In step 3, the iterative function based on the Newton's +method~\cite{newt70} and Weiestrass operator~\cite{Weierstrass03} is +applied. With this step the computation of roots will converge, +provided that all roots are different. - than in step 3 we apply the the iterative function based on the Newton's method~\cite{newt70} and Weiestrass operator~\cite{Weierstrass03}, wich will make it possible to converge to the roots solution, provided that all the root are different. - - At the end of each application of the iterative function, a stop condition is verified consists in stopping the iterative process when the whole of the modules of the roots are lower than a fixed value $\xi$. +In order to stop the iterative function, a stop condition is +applied. This condition checks that all the root modules are lower +than a fixed value $\xi$. \begin{equation} \label{eq:Aberth-Conv-Cond} \forall i \in [1,n];\vert\frac{z_{i}^{k}-z_{i}^{k-1}}{z_{i}^{k}}\vert<\xi \end{equation} \subsection{Improving Ehrlich-Aberth method} -With high degree polynomial, the Ehrlich-Aberth method suffer from overflow because the limited number in the mantissa of floating points representations, which makes the computation of $p(z)$ wrong when z is large. +With high degree polynomials, the Ehrlich-Aberth method suffers from +floating point overflows due to the mantissa of floating points +representations. This induces errors in the computation of $p(z)$ when +$z$ is large. Experimentally, it is very difficult to solve polynomials with Ehrlich-Aberth method and have roots which except the circle of unit, represented by the radius $r$ evaluated as: