Lehmer–Schur algorithm: Difference between revisions

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Undid revision 1126044387 by X-Fi6 (talk) There is no wrong formula and z/|z|^2 (sic!) equals 1/conj(z) for all non-zero z.
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Add: bibcode. | Use this bot. Report bugs. | Suggested by Abductive | Category:Root-finding algorithms‎ | #UCB_Category 17/37
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.<ref>{{cite journal |last1=Stewart |first1=G.W.III |title=On Lehmer's method for finding the zeros of a polynomial. |journal=Math. Comput. |date=1969 |volume=23 |issue=108 |pages=829–835 |doi=10.2307/2004970|jstor=2004970 }}</ref>
To avoid extreme scaling, or just for the sake of efficiency, one may start with testing a number of concentric disks for the number of included roots and thus reduce the region where roots occur to a number of narrow , concentric annuli. Repeating this procedure with another centre and combining the results, the said region becomes the union of intersections of such annuli.
<ref>{{cite journal |last1=Loewenthal |first1=Dan |title=Improvement on the Lehmer-Schur root detection method. |journal=J. Comput. Phys. |date=1993 |volume=109 |issue=2 |pages=164–168 |doi=10.1006/jcph.1993.1209|bibcode=1993JCoPh.109..164L }}</ref>
Finally, when a small disk is found that contains a single root, that root may be further approximated using other methods, e.g. [[Newton's method]].