#2943: [with patch, not ready for review] bug with power series and/or p-adics
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Reporter: jen | Owner: was
Type: defect | Status: new
Priority: critical | Milestone: sage-3.4.1
Component: number theory | Resolution:
Keywords: power series, p-adic extensions |
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Comment (by dmharvey):
Replying to [comment:17 kedlaya]:
Actually, there's nothing incorrect in your first example, except perhaps
the printing:
{{{
sage: C.<t> = PowerSeriesRing(Integers())
sage: D.<s> = PolynomialRing(C)
sage: z = 1 + (t + O(t^2))*s + (t^2 + O(t^3))*s^2
sage: z * z
(t^4 + O(t^5))*s^4 + (2*t + O(t^2))*s + 1
sage: (z*z).list()
[1, 2*t + O(t^2), O(t^2), O(t^3), t^4 + O(t^5)]
# let's do it "by hand"
sage: [sum([z[i] * z[n-i] for i in range(n+1)]) for n in range(5)]
[1, 2*t + O(t^2), 3*t^2 + O(t^3), 2*t^3 + O(t^4), t^4 + O(t^5)]
}}}
So it's not printing the "zero" coefficients, and it's losing precision,
but the result is correct up to the known precision.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2943#comment:19>
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