On Sun, Sep 20, 2009 at 11:49 AM, Tom Boothby <tomas.boot...@gmail.com> wrote:
>
> Maybe this is dumb -- but I'm perpetually bitten by it. Often times,
> I want to factor a list of numbers. Sometimes, a zero will pop up in
> the list, and I get an exception.
>
> Ok, so there isn't a unique prime factorization of zero. But, there
> isn't a unique prime factorization of a negative integer, either, but
> we don't raise exceptions there.
>
> My preference would be that factor works for all integers. It's not
> like it's hard to factor 0 or anything. We just return the
> factorization object [(0,1)].
I think I would prfer the empty list of primes and a "unit" of 0:
sage: X = Factorization([],unit=0)
sage: X
0
sage: X*X
0
sage: list(X)
[]
William
>
> Thoughts?
>
> Of course this is easy to solve:
>
> {{{
> for a,b,c in data:
> print a,b, factor(c)
> }}}
>
> just has to be
>
> {{{
> for a,b,c in data:
> if c != 0:
> print a, b, factor(c)
> else:
> print a,b, 0
> }}}
>
> but... the second is ugly and there's (IMHO) no reason for it.
>
> --tom
>
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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