#13393: Vector normalization
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Reporter: chrisjamesberg | Owner: Chris Berg
Type: defect | Status: needs_work
Priority: major | Milestone: sage-5.4
Component: linear algebra | Resolution:
Keywords: vector, normalize | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Chris Berg | Merged in:
Dependencies: | Stopgaps:
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Comment (by chrisjamesberg):
If you want to go that route, I could argue, what if your ring doesn't
have division...
I'm sure you have a good point, and I'm not as Sage savvy as most users
here, but from my perspective someone who is trying to use Sage for basic
functionality (like an undergrad trying to do homework) will be really
confused and frustrated if v.normalize() does not return a normalized
vector. In fact, this was how it was pointed out to me. I'm sure other
mathematicians use the functionality of what v.normalize() was doing
before, but these people are smart enough to write their own such code. Or
if it really is important it should be there, but shouldn't be called
normalize.
Replying to [comment:10 rbeezer]:
> What if your base ring/field does not have any square roots?
>
> {{{
> sage: v = vector([1,2,3])
> sage: n = v.norm()
> sage: n
> sqrt(14)
> sage: u = (1/n)*v
> sage: u.base_ring()
> Symbolic Ring
> }}}
>
> We start with a free module element (integer entries) and then we end up
in the Symbolic Ring (which is often hard to get out of).
>
> Over RDF/CDF I'd agree entirely. For '''exact''' linear algebra, I'm
not convinced.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13393#comment:14>
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