#7580: bugs in infinite polynomial ring
-----------------------+----------------------------------------------------
Reporter: was | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.3
Component: algebra | Keywords:
Work_issues: | Author:
Upstream: N/A | Reviewer:
Merged: |
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1. Here's one, from a fresh session in sage-4.3.alpha0:
{{{
sage: X.<x,y> = InfinitePolynomialRing(QQ)
sage: x[2^31]
Traceback (most recent
...
OverflowError: range() result has too many items
sage: x[100]
TypeError: ...
}}}
Why do we get a TypeError doing x[100] after the overflow error?
2. Here's another bug, probably the result of using string parsing (?),
but I'm not sure:
{{{
sage: X.<a,b> = InfinitePolynomialRing(QQ)
sage: a[100]
a100
sage: a[2/3]
1/3*a2
}}}
then the following weird error.
{{{
sage: a[Mod(2,3)]
Traceback (most recent ...)
...
TypeError: reduce() of empty sequence with no initial value
}}}
which is made weirder because the same input again suddenly works!
{{{
sage: a[Mod(2,3)]
a2
}}}
Here's one that is weird, due to not validating input before passing it
off to the libsingular coercion function:
{{{
sage: X.<a,b> = InfinitePolynomialRing(QQ)
sage: a[0]
a0
sage: a['0+5']
a0 + 5
sage: a['0+5^2']
a0 + 25
}}}
It's also really weird that the variable names have to be a single letter
and that the base ring has to be a field. Why?:
{{{
sage: X.<alpha,beta>= InfinitePolynomialRing(QQ)
Traceback (most recent call last):
ValueError: variable names must be of length 1
sage: X.<x,y> = InfinitePolynomialRing(ZZ)
Traceback (most recent call last):
TypeError: The base ring (= Integer Ring) must be a field
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7580>
Sage <http://www.sagemath.org>
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