#18979: avoid Maxima on creation of symbolic matrices
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Reporter: rws | Owner:
Type: | Status: needs_review
defect | Milestone: sage-6.9
Priority: major | Resolution:
Component: | Merged in:
linear algebra | Reviewers:
Keywords: | Work issues:
Authors: Nils | Commit:
Bruin | e42f2858c851693464226fad3532efedf50de3b2
Report Upstream: N/A | Stopgaps:
Branch: |
u/nbruin/18979 |
Dependencies: |
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Comment (by nbruin):
Replying to [comment:21 vdelecroix]:
> Note that your solution does not change anything to the problem
mentioned in the description of this ticket!
Well, it solves the problem for the example mentioned: for square matrices
and a single ring element as initialization it doesn't compare it to 0
anymore, so for square matrices, maxima is now avoided.
I think comparison in SR is smart enough that an explicit 0 compares equal
to 0 without punting to maxima. So maxima should only be hit if we have a
non-square matrix and the argument is not obviously 0. In that case it
probably isn't zero, and in any case the user deserves what they have
coming to them then.
In general, I think indeed that the generic matrix code shouldn't assume
equality- or zero-testing is particularly cheap, and hence avoid it unless
it's really necessary. The change here is a step in the right direction
and basically has the same effect of what rws was trying to do on his
branch.
--
Ticket URL: <http://trac.sagemath.org/ticket/18979#comment:22>
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