#4715: [with patch, needs review] Two small bugs in KodairaSymbol
---------------------------+------------------------------------------------
Reporter: cremona | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-3.2.2
Component: number theory | Resolution:
Keywords: |
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Changes (by cremona):
* summary: [with patch, not ready for review] Small bug in KodairaSymbol
=> [with patch, needs review] Two small bugs in
KodairaSymbol
Comment:
Fixing that also showed up the following completely independent bug (only
on 32-bit machines though):
{{{
sage: E=EllipticCurve('903b3')
sage: E.pari_curve()
<boom> (PariError: precision too low)
}}}
The second patch fixes that as well as the other (which only applied to
type I*0). Now I have checked tamagawa_index() for all curves in the
database up to conductor 10000 and all bad primes for each, so I hope
that's that.
To fix the pari precision problem I did a try/except which keeps doubling
the precision until it's ok. I hope that is not against the rules: if
pari's ellinit every crashes for a reason other than precision, this would
be an infinite loop.
In the course of this testing I found that looping through thousands of
curves ate up a lot of memory. I made a change so that for curves over
QQ, local_data() uses prime integers arther than prime ideals, and that
helps a bit, but there is still more memory begin eaten up than I would
like. For example:
{{{
sage: for e in cremona_curves(srange(11,10000)):
for p in e.conductor().support():
ld = e.local_data(p)
print e.cremona_label()
}}}
On my machine the used RAM creeps up gradually, hits 1GB at around
conductor 2400, and if I let it continue it starts to make my machine
really suffer at 1.7GB (no prizes for guessing the amount of RAM I have).
This might deserve a separate ticket.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4715#comment:4>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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