"William Stein" <[EMAIL PROTECTED]> writes: > On 5/17/07, Prof. J. E. Cremona <[EMAIL PROTECTED]> wrote: >> >> Problem: when executing the following, the last line takes forever and >> had to be killed: >> >> R = PolynomialRing(QQ, ['a','b','c','d','e'], 5) >> K = R.fraction_field() >> a,b,c,d,e = K.gens() >> >> ig = 12*a*e-3*b*d+c^2 >> jg = 72*a*c*e+9*b*c*d-27*a*d^2-27*e*b^2-2*c^3 >> hg = 8*a*c-3*b^2 >> deltag = 4*ig^3-jg^2 >> >> Ky.<y> = PolynomialRing(K,'y') >> phipoly = y^3-3*ig*y+jg >> >> What am I missing? > > Nothing -- You have found a subtle bug in SAGE's coercion code.
Such problems are legion. I've given up trying to fix them, because the details of munging every _coerce_ are too messy. I vote +1 to David Roe's commutative diagram approach precisely because of these issues. Nick PS. I also was doing elliptic curve calculations over the fraction field of a polynomial ring in SAGE... --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
