Creating an order in a number field --> infinite loop?

[craigcitro]

So I just tried the following:

sage: F.<alpha> = NumberField(x**4+3)
sage: F.order([alpha**2], allow_subfield=True)

and it seemed to go into an infinite loop. (Maybe I'm impatient, but it doesn't seem like it should take more than 2 seconds to do this, nevermind the minute I waited.) I haven't looked to see what the problem is at all.

Component: number theory

Issue created by migration from https://trac.sagemath.org/ticket/2216

[aghitza]

comment:1

It was indeed an infinite loop in absolute_order_from_module_generators(). See the attached patch.

[craigcitro]

comment:2

Looks good, with one trivial change: I think we should take out the line that says "This shows that trac #2216 has been fixed." This is useful to people editing the code, but not to the user -- and that's who the docstring should be for ...

[aghitza]

revised patch

[aghitza]

comment:3

Attachment: 2216-order_bug.patch.gz

I've replaced the patch with one in which "trac #2216 has been fixed" is changed into something more informative for the user ("an order in a subfield").

[sagetrac-mabshoff]

comment:4

I still think that mentioning the trac ticket when adding a specific doctest is a good thing. So combining both, i.e. a description that is useful for the user as well as (fixes #2216) in a good compromise.

Cheers,

Michael

[sagetrac-mabshoff]

comment:5

Merged in Sage 3.0.1.alpha0