#10317: how to copy/paste InfinitePolynomialRings?
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Reporter: zimmerma | Owner: AlexGhitza
Type: defect | Status: closed
Priority: minor | Milestone: sage-4.7
Component: basic arithmetic | Resolution: wontfix
Keywords: | Author:
Upstream: N/A | Reviewer:
Merged: | Work_issues:
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Changes (by SimonKing):
* status: new => closed
* resolution: => wontfix
Comment:
1. I see no reason whatsoever to expect that the string representation of
any object should return the object by copy-and-paste. Just think of any
element of a finite prime field: Its string representation will yield an
integer by copy-and-paste - not a prime field element. Or just think of
`ZZ`: Try to copy-and-paste its string representation...
This is why I resolve the ticket as wontfix.
2. There are two or three reasons why I decided to represent the elements
of an infinite polynomial ring the way they are.
(i) In the literature, the notation for the indices of variables is by
subscript. Hence, Latex style, `_`.
(ii) The arithmetic and, in particular, the Gröbner machinery, is based
on finite polynomial rings. It is reasonable to have the same variable
names both for the finite and the infinite polynomial ring. But `x[3]` is
no valid variable name of a finite polynomial ring.
(ii+1/2) I find `x_1` nicer to read than `x[1]`.
3. Here is your workaround:
{{{
sage: R.<a> = InfinitePolynomialRing(ZZ)
sage: f = a[0]+a[1]+a[2]
sage: f
a_2 + a_1 + a_0
sage: R('a_2 + a_1 + a_0')
a_2 + a_1 + a_0
sage: R('a_2 + a_1 + a_0')==f
True
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10317#comment:4>
Sage <http://www.sagemath.org>
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