On Wed, Jun 3, 2009 at 9:20 PM, James Parson <par...@hood.edu> wrote:
>
>> > Here is a variant on the original question: suppose I wanted to write
>> > a line that creates a polynomial ring whose variables are a_{ij} for i
>> > +j<=d. How should I do it? I might want to set this up, for example,
>>
>> sage: Inds = CartesianProduct(range(5), range(5))
>> sage: vars = ["a"+str(i)+str(j) for i,j in Inds]
>> sage: PolynomialRing(QQ,25,vars)
>> Multivariate Polynomial Ring in a00, a01, a02, a03, a04, a10, a11,
>> a12, a13, a14, a20, a21, a22, a23, a24, a30, a31, a32, a33, a34, a40,
>> a41, a42, a43, a44 over Rational Field
>
> Thanks again for the suggestions. I have one more foolish question
> about this sort of construction: if I type those lines into Sage and
> then type something like
>
> a00 + a11,
>
> I get an error
>
> NameError: name 'a00' is not defined.
>
> I read about this sort of thing in the Sage Tutorial, but I couldn't
> understand it well enough to figure out how to name the variables what
> I wanted. Is there any easy way to do this?
Sorry, I'm stuck here too. Can you just write R("a00")+R("a11") instead?
>
>
> Regards,
>
> James Parson
> >
>
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