I have several different vector space bases for an algebra A, and I have implemented this by having a class MyAlgebra, instances of which have an attribute _basis_name which is a string naming the basis. I have __cmp__ defined so that the basis is ignored: any two instances are canonically isomorphic, and there is good coercion between them.
Now, the attribute _basis_name just affects the _repr_ and _latex_ methods for elements of the algebra; it has no other effect. My question is this: when I multiply elements from algebras with two different bases, I can't figure out how the parent of the result is determined. Some documentation suggests that the parent should be determined by the left factor, but that is not consistently what's happening. I think I would like to force the result to have the same parent as the left-hand factor, but by the time elements get to the _mul_ method, their parents have been changed (via coercion), so I can't find out what that parent is. (Perhaps something is getting cached in the coercion process, so things are getting coerced to the cached algebra, not the left-hand parent?) What should I do? Does it sound like I'm doing something wrong, and if so, what should I investigate? I can try to post some sample code somewhere, but that will take a bit of work. Or I can post short snippets here, of course. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
