On Wed, Aug 26, 2009 at 7:56 PM, Robert
Bradshaw<rober...@math.washington.edu> wrote:
>>> x[1], and then x[1] would create another symbolic variable x[1][1].
>>>
>>
>> That sounds pretty easy to implement by defining __getitem__ for
>> symbolic variables, and making it cache its answer using a dictionary.
>
> I've advocated for this before--I think it's a great idea.
>
>> Should one only allow x[integer] or more generally x[anything
>> hashable]?
>
> I would say x[anything symbolic]. Thus one could do
>
> sage: var('x,a')
> sage: x[a]
> x[a]
> sage: x[a].subs(a=1)
> x[1]
>
> I don't think x[a].subs(x=y) should be y[a], but you should be able
> to sub for x[...] as a normal variable.
>
> - Robert
Yes, this makes a lot of sense to me, since it's very common in
mathematics to have expressions like x_i, where i is some variable.
So would we have
sage: latex(x[3])
x_{3}
William
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