X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/kahina_paper1.git/blobdiff_plain/e74bf528b696246b88bb8a5542efc542fd09788a..5771bd90bdc89ce5ca4a1947aca277e3101ea508:/paper.tex diff --git a/paper.tex b/paper.tex index 76b626e..c4fa445 100644 --- a/paper.tex +++ b/paper.tex @@ -308,7 +308,7 @@ but we prefer the latter one because we can use it to improve the Ehrlich-Aberth method and find the roots of very high degrees polynomials. More details are given in Section ~\ref{sec2}. \subsection{Convergence Condition} -The convergence condition determines the termination of the algorithm. It consists in stopping from running the iterative function when the roots are sufficiently stable. We consider that the method converges sufficiently when: +The convergence condition determines the termination of the algorithm. It consists in stopping the iterative function when the roots are sufficiently stable. We consider that the method converges sufficiently when: \begin{equation} \label{eq:Aberth-Conv-Cond} @@ -319,7 +319,8 @@ The convergence condition determines the termination of the algorithm. It consis \section{Improving the Ehrlich-Aberth Method for high degree polynomials with exp.log formulation} \label{sec2} -The Ehrlich-Aberth method implementation suffers of overflow problems. This +With high degree polynomial, the Ehrlich-Aberth method implementation, +as well as the Durand-Kerner implement, suffers from overflow problems. This situation occurs, for instance, in the case where a polynomial having positive coefficients and a large degree is computed at a point $\xi$ where $|\xi| > 1$, where $|x|$ stands for the modolus of a complex $x$. Indeed, the limited number in the @@ -347,7 +348,7 @@ Using the logarithm (eq.~\ref{deflncomplex}) and the exponential (eq.~\ref{defex manipulate lower absolute values and the roots for large polynomial's degrees can be looked for successfully~\cite{Karimall98}. Applying this solution for the Ehrlich-Aberth method we obtain the -iteration function with logarithm: +iteration function with exponential and logarithm: %%$$ \exp \bigl( \ln(p(z)_{k})-ln(\ln(p(z)_{k}^{'}))- \ln(1- \exp(\ln(p(z)_{k})-ln(\ln(p(z)_{k}^{'})+\ln\sum_{i\neq j}^{n}\frac{1}{z_{k}-z_{j}})$$ \begin{equation} \label{Log_H2}