#11767: elliptic_logarithm of high precision points often hangs forever
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Reporter: was | Owner: cremona
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.7.2
Component: elliptic curves | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by cremona):
Replying to [comment:11 zimmerma]:
> ok, after looking again, it seems that using {{{prec2 = 2*prec}}} is
overkill.
> Usually, what we do in MPFR is that we use as internal precision prec +
log2(prec) + a few bits.
> To avoid computing a log(), I suggest using {{{prec2 = prec + 40}}}
which should be large enough.
> With this change, William's example with prec=600 runs ok. John, if you
agree with that, I can
> make a new patch.
>
> Paul
I agree, that is fine. I put in 2*prec for testing and it worked (well,
for several months!) and the algorithm was fast enough that I never
bothered to work out a more sensible increase.
After today (Thursday 15/9/11) I'll be away for 8 days so please don't
wait for my approval to give the new patch a positive review assuming that
the tests pass, including the new doctest with William's example.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11767#comment:12>
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