#15364: Introduce factor_or_zero into global namespace
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Reporter: zabrocki | Owner:
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-6.0
Component: factorization | Resolution:
Keywords: | Merged in:
Authors: Mike Zabrocki | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/ticket/15364/zabrocki/factor_or_zero|
1e0e3da44e609c65c2b6b269f80991d01a33b844
Dependencies: | Stopgaps:
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Changes (by zabrocki):
* status: needs_review => needs_work
Comment:
> From the application you describe, I guess you're mostly interested in
application to SR (the first case) in which case the most appropriate
thing to do is probably to add a method `simplify_factor` to
SymbolicExpression, which could happily simplify the expression "0" to the
product "0". In the other cases, the code is just a lot clearer if people
specify their own little one-off function that does with 0 what they want.
I (and my colleagues that are likely to use this code) will probably be
working with algebras over polynomial rings/fraction fields or integer
coefficients. SR is rather slow so I don't use it much. This is a
convenience function. I can go through my list worksheets and could say
that in about 1/3 of them I've had to work around factor throwing errors
at me.
> For Factorization objects: I think you really don't want those to get
out into the wild when constructed with 0:
> {{{
> sage: a=Factorization([(0,1)])
> sage: b=Factorization([(2,1)])
> sage: a.gcd(b)
> 1
> sage: a^(-1)
> 0^-1
> }}}
> That's just wrong. I think that's even worse than getting an attribute
error on `.value()`.
You are right. We might need to clean up the factorization code so that
it handles the 0 object properly.
--
Ticket URL: <http://trac.sagemath.org/ticket/15364#comment:13>
Sage <http://www.sagemath.org>
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