Hi John,
On 21 Sep., 21:16, "John Cremona" <[EMAIL PROTECTED]> wrote:
> The long test in ell_finite_field.py which causes problems on this
> platform is this:
> sage: E = EllipticCurve('389a')
> sage: for p in prime_range(10000): #long time (~20s)
> ... if p != 389:
> ... G=E.change_ring(GF(p)).abelian_group()
>
> I would like to know if there is something going on there which can be fixed.
>
> Can you test these and see if they work:
>
> sage: for p in prime_range(10000):
> ... if p != 389:
> ... F=GF(p)
>
> and
>
> sage: for p in prime_range(10000):
> ... if p != 389:
> ... Ep=E.change_ring(GF(p))
>
> and
>
> sage: for p in prime_range(10000):
> ... if p != 389:
> ... G=E.change_ring(GF(p)).cardinality()
>
> Thanks,
>
> John
the following line works fine:
sage: for p in prime_range(10000):
... if p != 389:
... F=GF(p)
as does that one (note the 3000 instead the 10000):
sage: for p in prime_range(3000): #long time
(~20s)
... if p != 389:
... Ep = E.change_ring(GF(p))
but now with 4000 (yet no 10000) it fails:
sage: for p in prime_range(4000): #long time
(~20s)
... if p != 389:
... Ep = E.change_ring(GF(p))
with the following message:
...
sage -t -long devel/sage/sage/schemes/elliptic_curves/
ell_finite_field.py
halt 14
error: no more memory
System 5112k:5112k Appl 4598k/513k Malloc 4082k/5k Valloc 1024k/508k
Pages 144/112 Regions 2:2
A mysterious error (perphaps a memory error?) occurred, which may have
crashed doctest.
[37.2 s]
exit code: 768
----------------------------------------------------------------------
The following tests failed:
sage -t -long devel/sage/sage/schemes/elliptic_curves/
ell_finite_field.py
Total time for all tests: 37.2 seconds
...
Mysteriously, monitoring the RAM footprint during this half minute,
nothing strange seems to happen. Of the 2 GB physical memory, more
than 1.3 GB RAM is free at minimum all the time. Of the virtual RAM of
the Sage processes, there is one python process of some 360 MB or so,
and one gp processes of 600 MB or so, but that's it essentially.
Monitoring this half minute with "3000" as a prime boundary instead of
"4000" does not show any difference to me, especially the RAM
footprint of all the processes involved is the same (300+MB python,
600+MB gp), apart from passing the test :-).
For completeness, the following passes (the original line with only
"3000" instead of "10000"):
sage: for p in prime_range(3000): #long time
(~20s)
... if p != 389:
... G=E.change_ring(GF(p)).abelian_group()
So, "E.change_ring(GF(p))" is somehow the culprit, being called for
primes p up to 4000 (or 10000) instead of only up to 3000.
I' m curious if you can make sense of this --- I'll be online again
tomorrow evening.
Cheers,
gsw
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