#12777: Add signal handling to libecm.pyx
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Reporter: jdemeyer | Owner: tbd
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.0
Component: factorization | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Jeroen Demeyer | Merged in:
Dependencies: #12757 | Stopgaps:
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Comment (by zimmerma):
when recompiling Sage with this patch, I got a warning that variables f
and n were referenced before assignment. Maybe it happened before this
patch.
Some comments on the patch itself:
"The Elliptic Curve Method for Integer Factorization (GMP-ECM)": please
replace GMP-ECM by ECM, since GMP-ECM is only **one implementation** of
the ECM algorithm.
"Try to find a factor of a number": it would be better to say "integer",
or even "positive integer".
"number to be factored": replace by "integer to be factored"
About the example with the factor from 2^167^-1: the B1 bound 1e5 is not
enough to ensure
the factor 2349023 will always be found. By Hasse theorem, the group order
can be as large
as 2352089, and since GMP-ECM only guarantees a torsion of 12, B1=196003
is needed to ensure
the factor 2349023 is always found, whatever the curve (unfortunately, the
current interface
does not allow to specify the chosen curve).
"The following number is a Mersenne prime, so we will not find any
factors": this is not
entirely true, it might be that we find the input number itself if we are
lucky.
For the example with the two prime factors of 2^179^-1, in fact B1=1e4
ensures we will find always both of them, as any value B1 >= 113. I
suggest using B1=10 instead.
{{{ecmfactor(N/11, 100, verbose=True)}}}: please replace {{{N/11}}} by
{{{N//11}}}.
Paul
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12777#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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