On Wednesday, September 19, 2012 1:52:24 PM UTC-7, Robert Bradshaw wrote: > There is the issue that norm(v) does not always (often?) live in v for > exact v. Dropping to SR can be really slow, as can dropping to > QQ[sqrt(norm(v))], especially if several vectors are normalized then > used together (though I'm sure we could find/write a fairly efficient > multi-quadratic extension implantation that could be more generally > useful). >
Exactly. I'd feel a lot better about the proposed change if there was no way to ever end up in the symbolic ring (unless, of course, your vector began there). Having square roots of integers be symbolic (an inexact ring) causes no end of trouble when trying to do things like matrix decompositions over exact rings (such as starting over QQ). At least we have QQbar for square roots of rationals and integers. > This was pointed out to me by someone who teaches undergrads and found it frustrating that Sage was not doing the standard normalization. Making things more predictable for undergrads is always a good idea. Why don't we go all the way? Have normalization() return a vector over RDF/CDF. I think this is what "most people would think it should do." Rob -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To post to this group, send email to sage-devel@googlegroups.com. To unsubscribe from this group, send email to sage-devel+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
