| From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: WIP: rewrite numeric division |
| Date: | 2007-06-19 10:39:57 |
| Message-ID: | 87sl8o8bya.fsf@oxford.xeocode.com |
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| Lists: | pgsql-patches |
"Gregory Stark" <stark(at)enterprisedb(dot)com> writes:
> So your complaint about the existing code boils down to not having any
> rigorous way to know when to stop. I don't think Newton's method has that
> problem, at least not for simple polynomials. Any digits which don't change
> from one iteration to the next are definitely correct.
Er, I don't think that last sentence is correct. But I believe it is possible
to tell how many digits are accurate based on the difference between
successive estimates because you know how fast it converges (quadratically).
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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