Opened 12 years ago

Last modified 10 days ago

#10084 needs_review defect

Lazy power series are created with incorrect order

Reported by: Harald Schilly Owned by: Sage Combinat CC user
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: combinatorics Keywords: LazyPowerSeries
Cc: axel.bacher@…, Mike Hansen, Martin Rubey Merged in:
Authors: Mike Hansen Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps: todo

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Description

Reported by the "Report a Problem" Form:

When typing the following:

S = LazyPowerSeriesRing(ZZ)
one = S(0) + S(1)
one.order

I get a "Infinite series order" message. When asking for

one.coefficients(3)

I get "[0, 0, 0]".

Looking into the code sage/combinat/species/series.py, the _add_ method calls the _new method to create the sum series. Trying:

zero = S(0)
test_series = zero._new(lambda ao: Stream(const=1), lambda: 0)
test_series.order
test_series.coefficients(3)

I again get "Infinite series order" and "[0, 0, 0]".

As I understand it, the _new() method calls the init() method of LazyPowerSeries in the line:

new_fps = self.__class__(parent, stream=None, order=unk, aorder=self.aorder, aorder_changed=True, is_initialized=False)

If the value self.aorder is inf, this puts new_fps.aorder to inf, which (in the init() code), also puts new_fps.order to inf, which makes Sage think that the series has infinite order.

Changing the argument aorder=self.aorder to aorder=unk in the above line solved the problem. The sum of S(0) and S(1) should have order zero, and its first three coefficients should be [1, 0, 0].

The series test_series should also have order zero, and its coefficients should be [1, 1, 1].

Attachments (1)

trac_10084-lazy_power_series_order-mh.patch (2.6 KB) - added by Mike Hansen 10 years ago.

Download all attachments as: .zip

Change History (12)

comment:1 Changed 12 years ago by Burcin Erocal

Cc: Mike Hansen added
Component: symbolicscombinatorics
Owner: changed from Burcin Erocal to Sage Combinat CC user

Changed 10 years ago by Mike Hansen

comment:2 Changed 10 years ago by Mike Hansen

Authors: Mike Hansen
Status: newneeds_review

comment:3 Changed 10 years ago by Mike Hansen

Status: needs_reviewneeds_work

comment:4 Changed 9 years ago by Jeroen Demeyer

Milestone: sage-5.11sage-5.12

comment:5 Changed 9 years ago by Martin Rubey

Cc: Martin Rubey added
Keywords: LazyPowerSeries added

comment:6 Changed 9 years ago by Mike Hansen

A fix is in #15673

comment:7 Changed 9 years ago by For batch modifications

Milestone: sage-6.1sage-6.2

comment:8 Changed 8 years ago by For batch modifications

Milestone: sage-6.2sage-6.3

comment:9 Changed 8 years ago by For batch modifications

Milestone: sage-6.3sage-6.4

comment:10 Changed 7 years ago by Jakob Kroeker

Stopgaps: todo

comment:11 Changed 10 days ago by Martin Rubey

Milestone: sage-6.4sage-duplicate/invalid/wontfix
Status: needs_workneeds_review

This is no longer relevant, since #32367.

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