#12778: Incorrect coercion of matrix elements when from different rings
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Reporter: kcrisman | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: linear algebra | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by kcrisman):
I figured we used the `Sequence.universe` for this. Here's the problem in
`Sequence`.
{{{
for i in range(len(x)-1):
try:
x[i], x[i+1] = coerce.canonical_coercion(x[i],x[i+1])
}}}
This is fine for stepwise finding a universe, but what it does is try to
coerce things one by one, instead of looking at all of them as a whole
(which is probably slower, of course).
I say that there must be an easy way to fix the matrix code so that we
don't call `Sequence` immediately, but first use it to find a `universe`,
then make the new `Sequence` as in your code. That would fix this ticket.
Then we could have a different ticket or sage-devel discussion on whether
this `Sequence` behavior is, in fact, a bug.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12778#comment:6>
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