I already had a quick look at this when Hakan first posted, but came
to no instant conclusion -- except that there are quite a few
functions in the Sage-pari interface where precision is impossible or
difficult to set as one would hope.
For example:
sage: P=EllipticCurve('37a1').gens()[0]; P.height()
0.0511114082399688
The method ellheight of sage.libs.pari.gen.gen has no prec parameter
though the pari function it calls does. I'm sure there are other
places where the same happens. We could fix them piecemeal, or fo
through the whole pari interface systematically, which would be a big
job!
John
2008/8/26 William Stein <[EMAIL PROTECTED]>:
>
> On Fri, Aug 15, 2008 at 1:57 AM, Håkan Granath
> <[EMAIL PROTECTED]> wrote:
>>
>> Hi,
>>
>> Is this a bug or am I doing something stupid? I get different
>> precisions the first and second time I run the same command.
>>
>> ----------------------------------------------------------------------
>> | SAGE Version 3.0.6, Release Date: 2008-07-30 |
>> | Type notebook() for the GUI, and license() for information. |
>> ----------------------------------------------------------------------
>>
>> sage: E = EllipticCurve('37a')
>> sage: E.period_lattice().basis(prec=30)
>>
>> (2.993458646231959629832009979452508177797583791370132985340523378563250356987,
>>
>> 2.451389381986790060854224831866525225349617289144796614656471406129152899999*I)
>> sage: E.period_lattice().basis(prec=30)
>>
>> (2.9934586462319596298320099794525081777975837913701329853405233785632503569866829041203940673970514734358405271049472881941443872373720252543753766710932613753043332505965246252164473069072694510749057806365610445781725817135182427934263132488980086942438020870431669315,
>>
>> 2.4513893819867900608542248318665252253496172891447966146564714061291528999992568928911321280291810887126842188696618479754751998666167558016789381647830306324546902881738259304962523119593946698932473794558796569481958707269691493740581897037588157844669302474334546641*I)
>>
>>
>> Best regards,
>>
>> Håkan
>
>
> This is definitely a bug. The output precision should be as given by
> the prec option. The bug is caused by a mistake in the caching code,
> surely. This will likely be easy to fix. This is now
> trac #3954:
>
> http://trac.sagemath.org/sage_trac/ticket/3954
>
> >
>
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