Okay, Here's some code (in case anyone is interested, this was related
to a problem that appeared on the math-fun mailing list):
def ECurve(n,k):
vars = ['a%d_%d'%(n,i) for i in range(k)]
v = R.gens()
F = FractionField(K)
S.<x> = F[]
f = (x^n-1)//(x-1)
g = x^k + sum([v[i]*x^i for i in range(k)])
c = (f%g).coefficients()
return R.ideal([z.numerator() for z in c[1:]).groebner_basis()
def Curve1(n,k)
I = ECurve(n,k)
if len(I) == 0:
return I
R = I[0].parent()
II = R.ideal(I)
J = II.elimination_ideal(R.gen()[:-2])
S.<b1,b2> = QQ[]
phi = R.hom((k-2)*[S(0)] + [b1,b2])
return Curve(phi(J.gens()[0]))
C = Curve1(9,3)
print C.genus()
On Aug 5, 4:12 pm, William Stein <[email protected]> wrote:
> On Wed, Aug 5, 2009 at 1:09 PM, VictorMiller <[email protected]>wrote:
>
>
>
>
>
> > I was asking SAGE to do a calculation that I knew was probably
> > laborious -- I had a plane curve (over Q) and I wanted its genus. I
> > defined it with C=Curve(equation_in_two_variables) and then typed
>
> > C.genus()
>
> > after a while (I was in the notebook) I just got the mysterious error
> > message:
>
> > delaybeforesend: 0
>
> > when I expanded it, at the end there was a lot of stuff, but the
> > relevant line was
>
> > pexpect.TIMEOUT: Timeout exceeded in read_nonblocking().
> > <pexpect.spawn instance at 0xa1c170c>
> > command: /u/victor/sage/local/bin/Singular
>
> > So, there are two questions:
>
> > a) is it possible to give a more informative error message. It seems
> > obvious that singular just took
> > too long in getting back to sage.
>
> This is not obvious to me. That is really weird. Sage should wait forever
> for any subprocess to return. The time limit on reading is purposely
> disabled. Weird. Maybe the subprocess really crashed and the error
> message is just wrong? Or maybe something is screwy with pexpect. Can
> you post code? Has anybody else seen anything similar?
>
> William
>
> > b) is it possible to give a longer timeout (if I really want the
> > answer)?
>
> > Victor
>
> --
> William Stein
> Associate Professor of Mathematics
> University of Washingtonhttp://wstein.org
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