#9457: power series comparison should use padded_list
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Reporter: niles | Owner: malb
Type: defect | Status: needs_review
Priority: minor | Milestone: sage-5.1
Component: commutative algebra | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: niles | Merged in:
Dependencies: | Stopgaps:
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Changes (by niles):
* status: needs_work => needs_review
* work_issues: Fix bug in
sage.schemes.elliptic_curves.sha_tate.Sha.an_padic
=>
* milestone: sage-5.0 => sage-5.1
Old description:
> Comparison of power series uses list instead of padded_list; this means
> that power series equality can fail:
>
> {{{
> sage: A.<t> = PowerSeriesRing(ZZ)
> sage: g = t + t^3 + t^5 + O(t^6); g
> t + t^3 + t^5 + O(t^6)
> sage: [g == g.add_bigoh(i) for i in range(7)]
> [True, False, True, False, True, False, True]
> sage: g.add_bigoh(3).list()
> [0, 1]
> sage: g.add_bigoh(3).padded_list()
> [0, 1, 0]
> }}}
New description:
Comparison of power series uses list instead of padded_list; this means
that power series equality can fail:
{{{
sage: A.<t> = PowerSeriesRing(ZZ)
sage: g = t + t^3 + t^5 + O(t^6); g
t + t^3 + t^5 + O(t^6)
sage: [g == g.add_bigoh(i) for i in range(7)]
[True, False, True, False, True, False, True]
sage: g.add_bigoh(3).list()
[0, 1]
sage: g.add_bigoh(3).padded_list()
[0, 1, 0]
}}}
== Apply ==
* [attachment: trac_9457_power_series_eq_rebase.patch]
--
Comment:
Bugs in p-adics seem to have been fixed as of Sage 5.0.rc0, so this patch
passes all long tests in sage/schemes/elliptic_curves. Since
`padded_list` is quite a bit slower than `list`, I've reworked the patch
to keep using `list`, but to append zeroes to the end of those lists which
are too short.
Patchbot: apply [attachment: trac_9457_power_series_eq_rebase.patch]
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9457#comment:16>
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