On Aug 28, 2008, at 6:20 AM, John Cremona wrote: > > Thanks for your comments, David. I am having some success: > > sage: A = AbelianGroup([2,3]) > sage: A.list() > [1, f1, f1^2, f0, f0*f1, f0*f1^2] > sage: A = AbelianGroup([2,3],operation='+') > sage: A.list() > [0, f1, 2*f1, f0, f0+f1, f0+2*f1] > > sage: A = AbelianGroup([2,3], names='ab') > sage: A.list() > [1, b, b^2, a, a*b, a*b^2] > sage: A = AbelianGroup([2,3],names='ab',operation='+') > sage: A.list() > [0, b, 2*b, a, a+b, a+2*b] > > The one thing I cannot get to work in the additive case is (for > example) 2*g where g is a group element. I have tried all possible > combinations of __lmul__, _lmul_, __rmul__, _rmul_, but although I > have this ok: > > sage: a,b=A.gens() > sage: b._lmul_(20) > 2*b > sage: 2*b > > inputting 20*b gives an error: > TypeError Traceback (most recent > call last) > > /home/john/sage-3.1.final/<ipython console> in <module>() > > /home/john/sage-3.1.final/element.pyx in > sage.structure.element.RingElement.__mul__ > (sage/structure/element.c:9190)() > > /home/john/sage-3.1.final/coerce.pyx in > sage.structure.coerce.CoercionModel_cache_maps.bin_op > (sage/structure/coerce.c:6288)() > > TypeError: unsupported operand parent(s) for '*': 'Integer Ring' and > 'Additive Abelian Group isomorphic to C2 x C3' > > Maybe someone who understands coercion can tell me how to get > around this?
You need to implement _lmul_ and make sure the basering is Z. - Robert --~--~---------~--~----~------------~-------~--~----~ 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://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
