Hi I'm trying to write some code involving isogenies that will work over different types of fields (at least rational and finite and hopefully number fields too.) Part of the code includes the line:
fp.numerator()-j*fp.denominator() where fp is a polynomial in t over Qt = FractionField(PolynomialRing(QQ,'t') for the elliptic curve E = EllipticCurve([1,0,1,4, -6]); E we have sage: E.j_invariant() 9938375/21952 sage: type(E.j_invariant()) <type 'sage.rings.rational.Rational'> and this works fine but for sage: E = EllipticCurve(GF(13^4, 'a'),[2,8]) sage: E.j_invariant() 4 sage: type(E.j_invariant()) <type 'sage.rings.finite_field_givaro.FiniteField_givaroElement'> and so I get the error TypeError: unsupported operand parent(s) for '-': 'Univariate Polynomial Ring in t over Rational Field' and 'Univariate Polynomial Ring in t over Finite Field in a of size 13^4' I have tried replacing j with QQ(j), but I got the error TypeError: Unable to coerce 4 (<type 'sage.rings.finite_field_givaro.FiniteField_givaroElement'>) to Rational Not quite sure how to proceed! Thanks in advance, Jenny --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
