I had a small typo in the last code. The line that said F = FractionField(K)
should have read F = FractionField(R) also after the line that starts with "vars = " should be the line R = PolynomialRing(Rationals(),k,vars) On Aug 5, 4:59 pm, VictorMiller <victorsmil...@gmail.com> wrote: > 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 <wst...@gmail.com> wrote: > > > On Wed, Aug 5, 2009 at 1:09 PM, VictorMiller <victorsmil...@gmail.com>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 > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
