id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
10272 laurent series truncate behaviour different from power series truncate tkluck malb "There is the following difference in behaviour between truncate() for power series and laurent series:
{{{
sage: P. = PowerSeriesRing(QQ)
sage: L. = LaurentSeriesRing(QQ)
sage: f = p^2 + p^3 + p^5 +p^6 + O(p^7)
sage: g = l^2 + l^3 + l^5 +l^6 + O(l^7)
sage: f.truncate(6)
p^5 + p^3 + p^2
sage: g.truncate(6)
l^2 + l^3 + l^5 + O(l^6)
sage: f.truncate_powerseries(6)
p^2 + p^3 + p^5 + O(p^6)
}}}
The problem is simply that g.truncate() calls truncate_powerseries() on its underlying power series.
The attached patch changes LaurentSeries.truncate() such that is calls truncate() on the underlying powerseries. For the current behaviour, it also adds a method truncate_laurentseries() which calls truncate_powerseries() on the underlying powerseries.
In my opinion, the methods truncate_powerseries and truncate_laurentseries are superfluous since they are equivalent to add_bigoh()." defect closed minor sage-5.1 commutative algebra fixed laurent series, truncate sd40.5 sage-5.1.beta3 Timo Kluck Marshall Hampton, Jeroen Demeyer, Karl-Dieter Crisman N/A