#8389: Sage eats all memory trying to evaluate MatrixSpace(QQ, 2)['x']
---------------------------+------------------------------------------------
Reporter: mmezzarobba | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.6.2
Component: algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by davidloeffler):
The problem's not in the polynomial ring constructor per se:
{{{
sage: R = PolynomialRing(MatrixSpace(QQ, 2),'x'); R
Univariate Polynomial Ring in x over Full MatrixSpace of 2 by 2 dense
matrices over Rational Field
}}}
Almost nothing works with R because printing of elements is broken, but at
least you can construct it!
The problem reported above lies in the {{{R['x']}}} syntax; for some
reason, the "list" method of the matrix ring is getting called, and this
(of course) never terminates. If you try this with a matrix space over a
*finite* ring, the list call succeeds, and it tries to get the element of
index 'x' -- which fails because the string 'x' isn't an integer:
{{{
sage: MatrixSpace(GF(3), 2)['x']
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/masiao/<ipython console> in <module>()
/storage/masiao/sage-4.6.2.alpha1/local/lib/python2.6/site-
packages/sage/structure/parent.so in
sage.structure.parent.Parent.__getitem__ (sage/structure/parent.c:8072)()
TypeError: list indices must be integers, not str
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8389#comment:2>
Sage <http://www.sagemath.org>
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