#18589: isogeny efficiency improvement
-------------------------+-------------------------------------------------
Reporter: | Owner:
cremona | Status: needs_review
Type: | Milestone: sage-6.8
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
elliptic curves | Work issues:
Keywords: | Commit:
isogeny | ad56369f5def8060575b6567342dedb28a447293
Authors: John | Stopgaps:
Cremona |
Report Upstream: N/A |
Branch: |
u/cremona/18589 |
Dependencies: |
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Comment (by jdemeyer):
In the current implementation, you are computing
{{{
from sage.rings.arith import gcd
a = _least_semi_primitive(l)
m = E.multiplication_by_m(a, x_only=True)
F = psi_l.parent()
x = F.gen()
d = F(m.denominator())
n = F(m.numerator())
}}}
even when `factors_by_degree` is empty.
An easy optimization would be
{{{
if all(factors == [] for factors in factors_by_degree):
return ...
}}}
just before that block.
--
Ticket URL: <http://trac.sagemath.org/ticket/18589#comment:38>
Sage <http://www.sagemath.org>
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