#20693: Sage crashes when computing newforms
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Reporter: ehlen | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-7.3
Component: modular forms | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by ehlen):
@pbruin: Great! Thanks a lot for your work!
However, the pari alternative seems to be kind of slow (which is much
better than crashing, of course).
With the example I gave in #20749, the pari inversion takes about 7
minutes but the code below, which mimics the _invert_c function, runs in
about 1.5 minutes for me:
{{{
d = alpha.polynomial().denominator()
D = alpha.parent().absolute_polynomial().denominator()
r,s,tt =
xgcd(alpha.polynomial().numerator()*D,alpha.parent().absolute_polynomial().numerator()*d)
b = s*d/D
F = alpha.parent()
beta = F(F.polynomial_quotient_ring()(b))
}}}
I don't like the last line of the code and I still have to make sure I
understood everything correctly and it works in all cases but then I could
submit a patch for the number field element to use a variant of this code
as an alternative. What do you think?
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Ticket URL: <http://trac.sagemath.org/ticket/20693#comment:24>
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